{"api_version":"1","generated_at":"2026-09-07T19:49:06+00:00","cve":"CVE-2026-80819","urls":{"html":"https://cve.report/CVE-2026-80819","api":"https://cve.report/api/cve/CVE-2026-80819.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-80819","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-80819"},"summary":{"title":"Bluetooth: RFCOMM: take rfcomm_mutex for the deferred setup accept","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: RFCOMM: take rfcomm_mutex for the deferred setup accept\n\nrfcomm_sock_recvmsg() completes a deferred setup by calling\nrfcomm_dlc_accept() without holding any RFCOMM lock:\n\n\tif (test_and_clear_bit(RFCOMM_DEFER_SETUP, &d->flags)) {\n\t\trfcomm_dlc_accept(d);\n\t\treturn 0;\n\t}\n\nand rfcomm_dlc_accept() dereferences the session on its first line:\n\n\tstruct sock *sk = d->session->sock->sk;\n\nEvery other path that touches d->session runs under rfcomm_mutex:\nrfcomm_dlc_open(), rfcomm_dlc_close(), rfcomm_dlc_exists(),\nrfcomm_dlc_send_rpn(), and the RFCOMM thread through\nrfcomm_process_sessions(). rfcomm_connect_ind() is even documented as\n\"called under rfcomm_lock()\". This call site is the only one that skips\nit.\n\nThe RFCOMM_DEFER_SETUP bit looks like it serialises the accept against\nteardown, since __rfcomm_dlc_close() returns early when it wins the\ntest_and_clear. But rfcomm_recv_disc() forces the state first:\n\n\td->state = BT_CLOSED;\n\t__rfcomm_dlc_close(d, err);\n\nand the early return only covers BT_CONNECT, BT_CONFIG, BT_OPEN and\nBT_CONNECT2. With the state already BT_CLOSED that switch does not\nmatch, the bit is never consulted, and __rfcomm_dlc_close() falls\nthrough to rfcomm_dlc_unlink(), which sets d->session = NULL.\n\nSo a remote DISC on a deferred dlc clears the session while leaving\nRFCOMM_DEFER_SETUP set. The next recvmsg() then passes the\ntest_and_clear and dereferences a NULL session. No timing window is\nneeded: once the DISC has been processed, the dereference is\nunconditional.\n\nGive rfcomm_dlc_accept() the same shape as rfcomm_dlc_open() and\nrfcomm_dlc_close(): an exported wrapper that takes rfcomm_mutex and\nre-checks the session, around a __rfcomm_dlc_accept() that the two\nin-core callers, which already hold the mutex, keep using.\n\nReproduced on a KASAN + PROVE_LOCKING kernel with a BR/EDR peer emulated\nover /dev/vhci: the peer brings up an ACL link, opens L2CAP on the\nRFCOMM PSM, starts a session, opens a dlc on a channel bound with\nBT_DEFER_SETUP, and sends DISC after the socket is accepted. recv() on\nthe accepted socket then hits:\n\n  Oops: general protection fault\n  KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]\n  RIP: 0010:rfcomm_dlc_accept+0x54/0x350\n  Call Trace:\n    rfcomm_sock_recvmsg+0x1cd/0x230\n    sock_recvmsg+0x166/0x1c0\n    __sys_recvfrom+0x20d/0x300\n\n0x10 is the offset of sock in struct rfcomm_session. With this patch the\nsame run completes with recv() returning 0 and no report, and lockdep\nstays quiet, confirming rfcomm_mutex is still taken before lock_sock on\nthis path as it is on the thread side.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-04 16:18:09","updated_at":"2026-09-04 16:18:09"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/56f0aa75c7640e46397ef73bea251fcbef9150c0","name":"https://git.kernel.org/stable/c/56f0aa75c7640e46397ef73bea251fcbef9150c0","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/825b95561d7b7c393df9e7bc295451aaeadc3d18","name":"https://git.kernel.org/stable/c/825b95561d7b7c393df9e7bc295451aaeadc3d18","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/43a556b2fd43f2df6dded59c2e26560a27874c24","name":"https://git.kernel.org/stable/c/43a556b2fd43f2df6dded59c2e26560a27874c24","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/362726c9c6e56eea4262109183e49868c39ccd3a","name":"https://git.kernel.org/stable/c/362726c9c6e56eea4262109183e49868c39ccd3a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/355bfd57ca4ca881c6eb03ca813b440a094b1f44","name":"https://git.kernel.org/stable/c/355bfd57ca4ca881c6eb03ca813b440a094b1f44","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/d4b1a13b1eff2e80925c7368ffdeaaa50cba93df","name":"https://git.kernel.org/stable/c/d4b1a13b1eff2e80925c7368ffdeaaa50cba93df","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/d8d686dd5662a7c4745e4515f1237a9f3b7df181","name":"https://git.kernel.org/stable/c/d8d686dd5662a7c4745e4515f1237a9f3b7df181","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/eb71d5a1ea8ff2683e394b48ae3cd676037ab4c2","name":"https://git.kernel.org/stable/c/eb71d5a1ea8ff2683e394b48ae3cd676037ab4c2","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b405c2f96ae2e37375105881890f7738833b1d62","name":"https://git.kernel.org/stable/c/b405c2f96ae2e37375105881890f7738833b1d62","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-80819","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80819","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected bb23c0ab824653be4aa7dfca15b07b3059717004 d8d686dd5662a7c4745e4515f1237a9f3b7df181 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected bb23c0ab824653be4aa7dfca15b07b3059717004 eb71d5a1ea8ff2683e394b48ae3cd676037ab4c2 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected bb23c0ab824653be4aa7dfca15b07b3059717004 56f0aa75c7640e46397ef73bea251fcbef9150c0 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected bb23c0ab824653be4aa7dfca15b07b3059717004 362726c9c6e56eea4262109183e49868c39ccd3a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.10.267 5.10.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.218 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.185 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.154 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.106 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.47 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.11 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.1 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"80819","cve":"CVE-2026-80819","epss":"0.001950000","percentile":"0.092960000","score_date":"2026-09-06","updated_at":"2026-09-07 00:06:16"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/bluetooth/rfcomm/core.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"d8d686dd5662a7c4745e4515f1237a9f3b7df181","status":"affected","version":"bb23c0ab824653be4aa7dfca15b07b3059717004","versionType":"git"},{"lessThan":"eb71d5a1ea8ff2683e394b48ae3cd676037ab4c2","status":"affected","version":"bb23c0ab824653be4aa7dfca15b07b3059717004","versionType":"git"},{"lessThan":"56f0aa75c7640e46397ef73bea251fcbef9150c0","status":"affected","version":"bb23c0ab824653be4aa7dfca15b07b3059717004","versionType":"git"},{"lessThan":"362726c9c6e56eea4262109183e49868c39ccd3a","status":"affected","version":"bb23c0ab824653be4aa7dfca15b07b3059717004","versionType":"git"},{"lessThan":"825b95561d7b7c393df9e7bc295451aaeadc3d18","status":"affected","version":"bb23c0ab824653be4aa7dfca15b07b3059717004","versionType":"git"},{"lessThan":"d4b1a13b1eff2e80925c7368ffdeaaa50cba93df","status":"affected","version":"bb23c0ab824653be4aa7dfca15b07b3059717004","versionType":"git"},{"lessThan":"355bfd57ca4ca881c6eb03ca813b440a094b1f44","status":"affected","version":"bb23c0ab824653be4aa7dfca15b07b3059717004","versionType":"git"},{"lessThan":"b405c2f96ae2e37375105881890f7738833b1d62","status":"affected","version":"bb23c0ab824653be4aa7dfca15b07b3059717004","versionType":"git"},{"lessThan":"43a556b2fd43f2df6dded59c2e26560a27874c24","status":"affected","version":"bb23c0ab824653be4aa7dfca15b07b3059717004","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/bluetooth/rfcomm/core.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"2.6.30"},{"lessThan":"2.6.30","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.267","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.218","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.185","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.154","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.106","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.47","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.11","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.1","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.10.267","versionStartIncluding":"2.6.30","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.218","versionStartIncluding":"2.6.30","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.185","versionStartIncluding":"2.6.30","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.154","versionStartIncluding":"2.6.30","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.106","versionStartIncluding":"2.6.30","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.47","versionStartIncluding":"2.6.30","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.11","versionStartIncluding":"2.6.30","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.1","versionStartIncluding":"2.6.30","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"2.6.30","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: RFCOMM: take rfcomm_mutex for the deferred setup accept\n\nrfcomm_sock_recvmsg() completes a deferred setup by calling\nrfcomm_dlc_accept() without holding any RFCOMM lock:\n\n\tif (test_and_clear_bit(RFCOMM_DEFER_SETUP, &d->flags)) {\n\t\trfcomm_dlc_accept(d);\n\t\treturn 0;\n\t}\n\nand rfcomm_dlc_accept() dereferences the session on its first line:\n\n\tstruct sock *sk = d->session->sock->sk;\n\nEvery other path that touches d->session runs under rfcomm_mutex:\nrfcomm_dlc_open(), rfcomm_dlc_close(), rfcomm_dlc_exists(),\nrfcomm_dlc_send_rpn(), and the RFCOMM thread through\nrfcomm_process_sessions(). rfcomm_connect_ind() is even documented as\n\"called under rfcomm_lock()\". This call site is the only one that skips\nit.\n\nThe RFCOMM_DEFER_SETUP bit looks like it serialises the accept against\nteardown, since __rfcomm_dlc_close() returns early when it wins the\ntest_and_clear. But rfcomm_recv_disc() forces the state first:\n\n\td->state = BT_CLOSED;\n\t__rfcomm_dlc_close(d, err);\n\nand the early return only covers BT_CONNECT, BT_CONFIG, BT_OPEN and\nBT_CONNECT2. With the state already BT_CLOSED that switch does not\nmatch, the bit is never consulted, and __rfcomm_dlc_close() falls\nthrough to rfcomm_dlc_unlink(), which sets d->session = NULL.\n\nSo a remote DISC on a deferred dlc clears the session while leaving\nRFCOMM_DEFER_SETUP set. The next recvmsg() then passes the\ntest_and_clear and dereferences a NULL session. No timing window is\nneeded: once the DISC has been processed, the dereference is\nunconditional.\n\nGive rfcomm_dlc_accept() the same shape as rfcomm_dlc_open() and\nrfcomm_dlc_close(): an exported wrapper that takes rfcomm_mutex and\nre-checks the session, around a __rfcomm_dlc_accept() that the two\nin-core callers, which already hold the mutex, keep using.\n\nReproduced on a KASAN + PROVE_LOCKING kernel with a BR/EDR peer emulated\nover /dev/vhci: the peer brings up an ACL link, opens L2CAP on the\nRFCOMM PSM, starts a session, opens a dlc on a channel bound with\nBT_DEFER_SETUP, and sends DISC after the socket is accepted. recv() on\nthe accepted socket then hits:\n\n  Oops: general protection fault\n  KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]\n  RIP: 0010:rfcomm_dlc_accept+0x54/0x350\n  Call Trace:\n    rfcomm_sock_recvmsg+0x1cd/0x230\n    sock_recvmsg+0x166/0x1c0\n    __sys_recvfrom+0x20d/0x300\n\n0x10 is the offset of sock in struct rfcomm_session. With this patch the\nsame run completes with recv() returning 0 and no report, and lockdep\nstays quiet, confirming rfcomm_mutex is still taken before lock_sock on\nthis path as it is on the thread side."}],"providerMetadata":{"dateUpdated":"2026-09-04T15:13:40.309Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/d8d686dd5662a7c4745e4515f1237a9f3b7df181"},{"url":"https://git.kernel.org/stable/c/eb71d5a1ea8ff2683e394b48ae3cd676037ab4c2"},{"url":"https://git.kernel.org/stable/c/56f0aa75c7640e46397ef73bea251fcbef9150c0"},{"url":"https://git.kernel.org/stable/c/362726c9c6e56eea4262109183e49868c39ccd3a"},{"url":"https://git.kernel.org/stable/c/825b95561d7b7c393df9e7bc295451aaeadc3d18"},{"url":"https://git.kernel.org/stable/c/d4b1a13b1eff2e80925c7368ffdeaaa50cba93df"},{"url":"https://git.kernel.org/stable/c/355bfd57ca4ca881c6eb03ca813b440a094b1f44"},{"url":"https://git.kernel.org/stable/c/b405c2f96ae2e37375105881890f7738833b1d62"},{"url":"https://git.kernel.org/stable/c/43a556b2fd43f2df6dded59c2e26560a27874c24"}],"title":"Bluetooth: RFCOMM: take rfcomm_mutex for the deferred setup accept","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-80819","datePublished":"2026-09-04T15:13:40.309Z","dateReserved":"2026-08-26T14:34:25.795Z","dateUpdated":"2026-09-04T15:13:40.309Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-04 16:18:09","lastModifiedDate":"2026-09-04 16:18:09","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"80819","Ordinal":"1","Title":"Bluetooth: RFCOMM: take rfcomm_mutex for the deferred setup acce","CVE":"CVE-2026-80819","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"80819","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: RFCOMM: take rfcomm_mutex for the deferred setup accept\n\nrfcomm_sock_recvmsg() completes a deferred setup by calling\nrfcomm_dlc_accept() without holding any RFCOMM lock:\n\n\tif (test_and_clear_bit(RFCOMM_DEFER_SETUP, &d->flags)) {\n\t\trfcomm_dlc_accept(d);\n\t\treturn 0;\n\t}\n\nand rfcomm_dlc_accept() dereferences the session on its first line:\n\n\tstruct sock *sk = d->session->sock->sk;\n\nEvery other path that touches d->session runs under rfcomm_mutex:\nrfcomm_dlc_open(), rfcomm_dlc_close(), rfcomm_dlc_exists(),\nrfcomm_dlc_send_rpn(), and the RFCOMM thread through\nrfcomm_process_sessions(). rfcomm_connect_ind() is even documented as\n\"called under rfcomm_lock()\". This call site is the only one that skips\nit.\n\nThe RFCOMM_DEFER_SETUP bit looks like it serialises the accept against\nteardown, since __rfcomm_dlc_close() returns early when it wins the\ntest_and_clear. But rfcomm_recv_disc() forces the state first:\n\n\td->state = BT_CLOSED;\n\t__rfcomm_dlc_close(d, err);\n\nand the early return only covers BT_CONNECT, BT_CONFIG, BT_OPEN and\nBT_CONNECT2. With the state already BT_CLOSED that switch does not\nmatch, the bit is never consulted, and __rfcomm_dlc_close() falls\nthrough to rfcomm_dlc_unlink(), which sets d->session = NULL.\n\nSo a remote DISC on a deferred dlc clears the session while leaving\nRFCOMM_DEFER_SETUP set. The next recvmsg() then passes the\ntest_and_clear and dereferences a NULL session. No timing window is\nneeded: once the DISC has been processed, the dereference is\nunconditional.\n\nGive rfcomm_dlc_accept() the same shape as rfcomm_dlc_open() and\nrfcomm_dlc_close(): an exported wrapper that takes rfcomm_mutex and\nre-checks the session, around a __rfcomm_dlc_accept() that the two\nin-core callers, which already hold the mutex, keep using.\n\nReproduced on a KASAN + PROVE_LOCKING kernel with a BR/EDR peer emulated\nover /dev/vhci: the peer brings up an ACL link, opens L2CAP on the\nRFCOMM PSM, starts a session, opens a dlc on a channel bound with\nBT_DEFER_SETUP, and sends DISC after the socket is accepted. recv() on\nthe accepted socket then hits:\n\n  Oops: general protection fault\n  KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]\n  RIP: 0010:rfcomm_dlc_accept+0x54/0x350\n  Call Trace:\n    rfcomm_sock_recvmsg+0x1cd/0x230\n    sock_recvmsg+0x166/0x1c0\n    __sys_recvfrom+0x20d/0x300\n\n0x10 is the offset of sock in struct rfcomm_session. With this patch the\nsame run completes with recv() returning 0 and no report, and lockdep\nstays quiet, confirming rfcomm_mutex is still taken before lock_sock on\nthis path as it is on the thread side.","Type":"Description","Title":"Bluetooth: RFCOMM: take rfcomm_mutex for the deferred setup acce"}]}}}