{"api_version":"1","generated_at":"2026-04-22T19:52:04+00:00","cve":"CVE-2026-31503","urls":{"html":"https://cve.report/CVE-2026-31503","api":"https://cve.report/api/cve/CVE-2026-31503.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-31503","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-31503"},"summary":{"title":"udp: Fix wildcard bind conflict check when using hash2","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nudp: Fix wildcard bind conflict check when using hash2\n\nWhen binding a udp_sock to a local address and port, UDP uses\ntwo hashes (udptable->hash and udptable->hash2) for collision\ndetection. The current code switches to \"hash2\" when\nhslot->count > 10.\n\n\"hash2\" is keyed by local address and local port.\n\"hash\" is keyed by local port only.\n\nThe issue can be shown in the following bind sequence (pseudo code):\n\nbind(fd1,  \"[fd00::1]:8888\")\nbind(fd2,  \"[fd00::2]:8888\")\nbind(fd3,  \"[fd00::3]:8888\")\nbind(fd4,  \"[fd00::4]:8888\")\nbind(fd5,  \"[fd00::5]:8888\")\nbind(fd6,  \"[fd00::6]:8888\")\nbind(fd7,  \"[fd00::7]:8888\")\nbind(fd8,  \"[fd00::8]:8888\")\nbind(fd9,  \"[fd00::9]:8888\")\nbind(fd10, \"[fd00::10]:8888\")\n\n/* Correctly return -EADDRINUSE because \"hash\" is used\n * instead of \"hash2\". udp_lib_lport_inuse() detects the\n * conflict.\n */\nbind(fail_fd, \"[::]:8888\")\n\n/* After one more socket is bound to \"[fd00::11]:8888\",\n * hslot->count exceeds 10 and \"hash2\" is used instead.\n */\nbind(fd11, \"[fd00::11]:8888\")\nbind(fail_fd, \"[::]:8888\")      /* succeeds unexpectedly */\n\nThe same issue applies to the IPv4 wildcard address \"0.0.0.0\"\nand the IPv4-mapped wildcard address \"::ffff:0.0.0.0\". For\nexample, if there are existing sockets bound to\n\"192.168.1.[1-11]:8888\", then binding \"0.0.0.0:8888\" or\n\"[::ffff:0.0.0.0]:8888\" can also miss the conflict when\nhslot->count > 10.\n\nTCP inet_csk_get_port() already has the correct check in\ninet_use_bhash2_on_bind(). Rename it to\ninet_use_hash2_on_bind() and move it to inet_hashtables.h\nso udp.c can reuse it in this fix.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-04-22 14:16:48","updated_at":"2026-04-22 14:16:48"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/18d84c45def3671d5c89fbdd5d4ab8a3217fe4b4","name":"https://git.kernel.org/stable/c/18d84c45def3671d5c89fbdd5d4ab8a3217fe4b4","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/2297e38114316b26ae02f2d205c49b5511c5ed55","name":"https://git.kernel.org/stable/c/2297e38114316b26ae02f2d205c49b5511c5ed55","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/d6ace0dbcbb7fd285738bb87b42b71b01858c952","name":"https://git.kernel.org/stable/c/d6ace0dbcbb7fd285738bb87b42b71b01858c952","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/0a360f7f73a06ac88f18917055fbcc79694252d7","name":"https://git.kernel.org/stable/c/0a360f7f73a06ac88f18917055fbcc79694252d7","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/e537dd15d0d4ad989d56a1021290f0c674dd8b28","name":"https://git.kernel.org/stable/c/e537dd15d0d4ad989d56a1021290f0c674dd8b28","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/f1bed05a832ae79be5f7a105da56810eaa59a5f1","name":"https://git.kernel.org/stable/c/f1bed05a832ae79be5f7a105da56810eaa59a5f1","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-31503","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31503","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 30fff9231fad757c061285e347b33c5149c2c2e4 d6ace0dbcbb7fd285738bb87b42b71b01858c952 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 30fff9231fad757c061285e347b33c5149c2c2e4 2297e38114316b26ae02f2d205c49b5511c5ed55 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 30fff9231fad757c061285e347b33c5149c2c2e4 f1bed05a832ae79be5f7a105da56810eaa59a5f1 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 30fff9231fad757c061285e347b33c5149c2c2e4 18d84c45def3671d5c89fbdd5d4ab8a3217fe4b4 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 30fff9231fad757c061285e347b33c5149c2c2e4 0a360f7f73a06ac88f18917055fbcc79694252d7 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 30fff9231fad757c061285e347b33c5149c2c2e4 e537dd15d0d4ad989d56a1021290f0c674dd8b28 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2.6.33","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 2.6.33 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.168 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.131 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.80 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.21 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.19.11 6.19.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["include/net/inet_hashtables.h","net/ipv4/inet_connection_sock.c","net/ipv4/udp.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"d6ace0dbcbb7fd285738bb87b42b71b01858c952","status":"affected","version":"30fff9231fad757c061285e347b33c5149c2c2e4","versionType":"git"},{"lessThan":"2297e38114316b26ae02f2d205c49b5511c5ed55","status":"affected","version":"30fff9231fad757c061285e347b33c5149c2c2e4","versionType":"git"},{"lessThan":"f1bed05a832ae79be5f7a105da56810eaa59a5f1","status":"affected","version":"30fff9231fad757c061285e347b33c5149c2c2e4","versionType":"git"},{"lessThan":"18d84c45def3671d5c89fbdd5d4ab8a3217fe4b4","status":"affected","version":"30fff9231fad757c061285e347b33c5149c2c2e4","versionType":"git"},{"lessThan":"0a360f7f73a06ac88f18917055fbcc79694252d7","status":"affected","version":"30fff9231fad757c061285e347b33c5149c2c2e4","versionType":"git"},{"lessThan":"e537dd15d0d4ad989d56a1021290f0c674dd8b28","status":"affected","version":"30fff9231fad757c061285e347b33c5149c2c2e4","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["include/net/inet_hashtables.h","net/ipv4/inet_connection_sock.c","net/ipv4/udp.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"2.6.33"},{"lessThan":"2.6.33","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.168","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.131","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.80","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.21","versionType":"semver"},{"lessThanOrEqual":"6.19.*","status":"unaffected","version":"6.19.11","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.0","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.168","versionStartIncluding":"2.6.33","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.131","versionStartIncluding":"2.6.33","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.80","versionStartIncluding":"2.6.33","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.21","versionStartIncluding":"2.6.33","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.19.11","versionStartIncluding":"2.6.33","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.0","versionStartIncluding":"2.6.33","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nudp: Fix wildcard bind conflict check when using hash2\n\nWhen binding a udp_sock to a local address and port, UDP uses\ntwo hashes (udptable->hash and udptable->hash2) for collision\ndetection. The current code switches to \"hash2\" when\nhslot->count > 10.\n\n\"hash2\" is keyed by local address and local port.\n\"hash\" is keyed by local port only.\n\nThe issue can be shown in the following bind sequence (pseudo code):\n\nbind(fd1,  \"[fd00::1]:8888\")\nbind(fd2,  \"[fd00::2]:8888\")\nbind(fd3,  \"[fd00::3]:8888\")\nbind(fd4,  \"[fd00::4]:8888\")\nbind(fd5,  \"[fd00::5]:8888\")\nbind(fd6,  \"[fd00::6]:8888\")\nbind(fd7,  \"[fd00::7]:8888\")\nbind(fd8,  \"[fd00::8]:8888\")\nbind(fd9,  \"[fd00::9]:8888\")\nbind(fd10, \"[fd00::10]:8888\")\n\n/* Correctly return -EADDRINUSE because \"hash\" is used\n * instead of \"hash2\". udp_lib_lport_inuse() detects the\n * conflict.\n */\nbind(fail_fd, \"[::]:8888\")\n\n/* After one more socket is bound to \"[fd00::11]:8888\",\n * hslot->count exceeds 10 and \"hash2\" is used instead.\n */\nbind(fd11, \"[fd00::11]:8888\")\nbind(fail_fd, \"[::]:8888\")      /* succeeds unexpectedly */\n\nThe same issue applies to the IPv4 wildcard address \"0.0.0.0\"\nand the IPv4-mapped wildcard address \"::ffff:0.0.0.0\". For\nexample, if there are existing sockets bound to\n\"192.168.1.[1-11]:8888\", then binding \"0.0.0.0:8888\" or\n\"[::ffff:0.0.0.0]:8888\" can also miss the conflict when\nhslot->count > 10.\n\nTCP inet_csk_get_port() already has the correct check in\ninet_use_bhash2_on_bind(). Rename it to\ninet_use_hash2_on_bind() and move it to inet_hashtables.h\nso udp.c can reuse it in this fix."}],"providerMetadata":{"dateUpdated":"2026-04-22T13:54:23.221Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/d6ace0dbcbb7fd285738bb87b42b71b01858c952"},{"url":"https://git.kernel.org/stable/c/2297e38114316b26ae02f2d205c49b5511c5ed55"},{"url":"https://git.kernel.org/stable/c/f1bed05a832ae79be5f7a105da56810eaa59a5f1"},{"url":"https://git.kernel.org/stable/c/18d84c45def3671d5c89fbdd5d4ab8a3217fe4b4"},{"url":"https://git.kernel.org/stable/c/0a360f7f73a06ac88f18917055fbcc79694252d7"},{"url":"https://git.kernel.org/stable/c/e537dd15d0d4ad989d56a1021290f0c674dd8b28"}],"title":"udp: Fix wildcard bind conflict check when using hash2","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-31503","datePublished":"2026-04-22T13:54:23.221Z","dateReserved":"2026-03-09T15:48:24.105Z","dateUpdated":"2026-04-22T13:54:23.221Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-04-22 14:16:48","lastModifiedDate":"2026-04-22 14:16:48","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"31503","Ordinal":"1","Title":"udp: Fix wildcard bind conflict check when using hash2","CVE":"CVE-2026-31503","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"31503","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nudp: Fix wildcard bind conflict check when using hash2\n\nWhen binding a udp_sock to a local address and port, UDP uses\ntwo hashes (udptable->hash and udptable->hash2) for collision\ndetection. The current code switches to \"hash2\" when\nhslot->count > 10.\n\n\"hash2\" is keyed by local address and local port.\n\"hash\" is keyed by local port only.\n\nThe issue can be shown in the following bind sequence (pseudo code):\n\nbind(fd1,  \"[fd00::1]:8888\")\nbind(fd2,  \"[fd00::2]:8888\")\nbind(fd3,  \"[fd00::3]:8888\")\nbind(fd4,  \"[fd00::4]:8888\")\nbind(fd5,  \"[fd00::5]:8888\")\nbind(fd6,  \"[fd00::6]:8888\")\nbind(fd7,  \"[fd00::7]:8888\")\nbind(fd8,  \"[fd00::8]:8888\")\nbind(fd9,  \"[fd00::9]:8888\")\nbind(fd10, \"[fd00::10]:8888\")\n\n/* Correctly return -EADDRINUSE because \"hash\" is used\n * instead of \"hash2\". udp_lib_lport_inuse() detects the\n * conflict.\n */\nbind(fail_fd, \"[::]:8888\")\n\n/* After one more socket is bound to \"[fd00::11]:8888\",\n * hslot->count exceeds 10 and \"hash2\" is used instead.\n */\nbind(fd11, \"[fd00::11]:8888\")\nbind(fail_fd, \"[::]:8888\")      /* succeeds unexpectedly */\n\nThe same issue applies to the IPv4 wildcard address \"0.0.0.0\"\nand the IPv4-mapped wildcard address \"::ffff:0.0.0.0\". For\nexample, if there are existing sockets bound to\n\"192.168.1.[1-11]:8888\", then binding \"0.0.0.0:8888\" or\n\"[::ffff:0.0.0.0]:8888\" can also miss the conflict when\nhslot->count > 10.\n\nTCP inet_csk_get_port() already has the correct check in\ninet_use_bhash2_on_bind(). Rename it to\ninet_use_hash2_on_bind() and move it to inet_hashtables.h\nso udp.c can reuse it in this fix.","Type":"Description","Title":"udp: Fix wildcard bind conflict check when using hash2"}]}}}