{"api_version":"1","generated_at":"2026-07-23T12:51:56+00:00","cve":"CVE-2025-21796","urls":{"html":"https://cve.report/CVE-2025-21796","api":"https://cve.report/api/cve/CVE-2025-21796.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2025-21796","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2025-21796"},"summary":{"title":"nfsd: clear acl_access/acl_default after releasing them","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: clear acl_access/acl_default after releasing them\n\nIf getting acl_default fails, acl_access and acl_default will be released\nsimultaneously. However, acl_access will still retain a pointer pointing\nto the released posix_acl, which will trigger a WARNING in\nnfs3svc_release_getacl like this:\n\n------------[ cut here ]------------\nrefcount_t: underflow; use-after-free.\nWARNING: CPU: 26 PID: 3199 at lib/refcount.c:28\nrefcount_warn_saturate+0xb5/0x170\nModules linked in:\nCPU: 26 UID: 0 PID: 3199 Comm: nfsd Not tainted\n6.12.0-rc6-00079-g04ae226af01f-dirty #8\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS\n1.16.1-2.fc37 04/01/2014\nRIP: 0010:refcount_warn_saturate+0xb5/0x170\nCode: cc cc 0f b6 1d b3 20 a5 03 80 fb 01 0f 87 65 48 d8 00 83 e3 01 75\ne4 48 c7 c7 c0 3b 9b 85 c6 05 97 20 a5 03 01 e8 fb 3e 30 ff <0f> 0b eb\ncd 0f b6 1d 8a3\nRSP: 0018:ffffc90008637cd8 EFLAGS: 00010282\nRAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff83904fde\nRDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffff88871ed36380\nRBP: ffff888158beeb40 R08: 0000000000000001 R09: fffff520010c6f56\nR10: ffffc90008637ab7 R11: 0000000000000001 R12: 0000000000000001\nR13: ffff888140e77400 R14: ffff888140e77408 R15: ffffffff858b42c0\nFS:  0000000000000000(0000) GS:ffff88871ed00000(0000)\nknlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 0000562384d32158 CR3: 000000055cc6a000 CR4: 00000000000006f0\nDR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\nDR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\nCall Trace:\n <TASK>\n ? refcount_warn_saturate+0xb5/0x170\n ? __warn+0xa5/0x140\n ? refcount_warn_saturate+0xb5/0x170\n ? report_bug+0x1b1/0x1e0\n ? handle_bug+0x53/0xa0\n ? exc_invalid_op+0x17/0x40\n ? asm_exc_invalid_op+0x1a/0x20\n ? tick_nohz_tick_stopped+0x1e/0x40\n ? refcount_warn_saturate+0xb5/0x170\n ? refcount_warn_saturate+0xb5/0x170\n nfs3svc_release_getacl+0xc9/0xe0\n svc_process_common+0x5db/0xb60\n ? __pfx_svc_process_common+0x10/0x10\n ? __rcu_read_unlock+0x69/0xa0\n ? __pfx_nfsd_dispatch+0x10/0x10\n ? svc_xprt_received+0xa1/0x120\n ? xdr_init_decode+0x11d/0x190\n svc_process+0x2a7/0x330\n svc_handle_xprt+0x69d/0x940\n svc_recv+0x180/0x2d0\n nfsd+0x168/0x200\n ? __pfx_nfsd+0x10/0x10\n kthread+0x1a2/0x1e0\n ? kthread+0xf4/0x1e0\n ? __pfx_kthread+0x10/0x10\n ret_from_fork+0x34/0x60\n ? __pfx_kthread+0x10/0x10\n ret_from_fork_asm+0x1a/0x30\n </TASK>\nKernel panic - not syncing: kernel: panic_on_warn set ...\n\nClear acl_access/acl_default after posix_acl_release is called to prevent\nUAF from being triggered.","state":"PUBLISHED","assigner":"Linux","published_at":"2025-02-27 03:15:20","updated_at":"2026-07-14 13:17:23"},"problem_types":["CWE-416","CWE-416 CWE-416 Use After 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MFP","vendor":"Siemens","versions":[{"lessThan":"*","status":"affected","version":"V3.1.6","versionType":"custom"}]}],"providerMetadata":{"dateUpdated":"2026-07-14T12:40:10.487Z","orgId":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e","shortName":"siemens-SADP"},"references":[{"url":"https://cert-portal.siemens.com/productcert/html/ssa-265688.html"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-082556.html"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-019113.html"}],"x_adpType":"supplier"}],"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/nfsd/nfs2acl.c","fs/nfsd/nfs3acl.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"8a1737ae42c928384ab6447f6ee1a882510e85fa","status":"affected","version":"a257cdd0e2179630d3201c32ba14d7fcb3c3a055","versionType":"git"},{"lessThan":"6f7cfee1a316891890c505563aa54f3476db52fd","status":"affected","version":"a257cdd0e2179630d3201c32ba14d7fcb3c3a055","versionType":"git"},{"lessThan":"2e59b2b68782519560b3d6a41dd66a3d01a01cd3","status":"affected","version":"a257cdd0e2179630d3201c32ba14d7fcb3c3a055","versionType":"git"},{"lessThan":"55d947315fb5f67a35e4e1d3e01bb886b9c6decf","status":"affected","version":"a257cdd0e2179630d3201c32ba14d7fcb3c3a055","versionType":"git"},{"lessThan":"f8d871523142f7895f250a856f8c4a4181614510","status":"affected","version":"a257cdd0e2179630d3201c32ba14d7fcb3c3a055","versionType":"git"},{"lessThan":"1fd94884174bd20beb1773990fd3b1aa877688d9","status":"affected","version":"a257cdd0e2179630d3201c32ba14d7fcb3c3a055","versionType":"git"},{"lessThan":"7faf14a7b0366f153284db0ad3347c457ea70136","status":"affected","version":"a257cdd0e2179630d3201c32ba14d7fcb3c3a055","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/nfsd/nfs2acl.c","fs/nfsd/nfs3acl.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"2.6.13"},{"lessThan":"2.6.13","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.235","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.179","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.129","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.79","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.16","versionType":"semver"},{"lessThanOrEqual":"6.13.*","status":"unaffected","version":"6.13.4","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"6.14","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.10.235","versionStartIncluding":"2.6.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.179","versionStartIncluding":"2.6.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.129","versionStartIncluding":"2.6.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.79","versionStartIncluding":"2.6.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.16","versionStartIncluding":"2.6.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.13.4","versionStartIncluding":"2.6.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.14","versionStartIncluding":"2.6.13","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: clear acl_access/acl_default after releasing them\n\nIf getting acl_default fails, acl_access and acl_default will be released\nsimultaneously. However, acl_access will still retain a pointer pointing\nto the released posix_acl, which will trigger a WARNING in\nnfs3svc_release_getacl like this:\n\n------------[ cut here ]------------\nrefcount_t: underflow; use-after-free.\nWARNING: CPU: 26 PID: 3199 at lib/refcount.c:28\nrefcount_warn_saturate+0xb5/0x170\nModules linked in:\nCPU: 26 UID: 0 PID: 3199 Comm: nfsd Not tainted\n6.12.0-rc6-00079-g04ae226af01f-dirty #8\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS\n1.16.1-2.fc37 04/01/2014\nRIP: 0010:refcount_warn_saturate+0xb5/0x170\nCode: cc cc 0f b6 1d b3 20 a5 03 80 fb 01 0f 87 65 48 d8 00 83 e3 01 75\ne4 48 c7 c7 c0 3b 9b 85 c6 05 97 20 a5 03 01 e8 fb 3e 30 ff <0f> 0b eb\ncd 0f b6 1d 8a3\nRSP: 0018:ffffc90008637cd8 EFLAGS: 00010282\nRAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff83904fde\nRDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffff88871ed36380\nRBP: ffff888158beeb40 R08: 0000000000000001 R09: fffff520010c6f56\nR10: ffffc90008637ab7 R11: 0000000000000001 R12: 0000000000000001\nR13: ffff888140e77400 R14: ffff888140e77408 R15: ffffffff858b42c0\nFS:  0000000000000000(0000) GS:ffff88871ed00000(0000)\nknlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 0000562384d32158 CR3: 000000055cc6a000 CR4: 00000000000006f0\nDR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\nDR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\nCall Trace:\n <TASK>\n ? refcount_warn_saturate+0xb5/0x170\n ? __warn+0xa5/0x140\n ? refcount_warn_saturate+0xb5/0x170\n ? report_bug+0x1b1/0x1e0\n ? handle_bug+0x53/0xa0\n ? exc_invalid_op+0x17/0x40\n ? asm_exc_invalid_op+0x1a/0x20\n ? tick_nohz_tick_stopped+0x1e/0x40\n ? refcount_warn_saturate+0xb5/0x170\n ? refcount_warn_saturate+0xb5/0x170\n nfs3svc_release_getacl+0xc9/0xe0\n svc_process_common+0x5db/0xb60\n ? __pfx_svc_process_common+0x10/0x10\n ? __rcu_read_unlock+0x69/0xa0\n ? __pfx_nfsd_dispatch+0x10/0x10\n ? svc_xprt_received+0xa1/0x120\n ? xdr_init_decode+0x11d/0x190\n svc_process+0x2a7/0x330\n svc_handle_xprt+0x69d/0x940\n svc_recv+0x180/0x2d0\n nfsd+0x168/0x200\n ? __pfx_nfsd+0x10/0x10\n kthread+0x1a2/0x1e0\n ? kthread+0xf4/0x1e0\n ? __pfx_kthread+0x10/0x10\n ret_from_fork+0x34/0x60\n ? __pfx_kthread+0x10/0x10\n ret_from_fork_asm+0x1a/0x30\n </TASK>\nKernel panic - not syncing: kernel: panic_on_warn set ...\n\nClear acl_access/acl_default after posix_acl_release is called to prevent\nUAF from being triggered."}],"providerMetadata":{"dateUpdated":"2026-05-11T21:06:39.968Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/8a1737ae42c928384ab6447f6ee1a882510e85fa"},{"url":"https://git.kernel.org/stable/c/6f7cfee1a316891890c505563aa54f3476db52fd"},{"url":"https://git.kernel.org/stable/c/2e59b2b68782519560b3d6a41dd66a3d01a01cd3"},{"url":"https://git.kernel.org/stable/c/55d947315fb5f67a35e4e1d3e01bb886b9c6decf"},{"url":"https://git.kernel.org/stable/c/f8d871523142f7895f250a856f8c4a4181614510"},{"url":"https://git.kernel.org/stable/c/1fd94884174bd20beb1773990fd3b1aa877688d9"},{"url":"https://git.kernel.org/stable/c/7faf14a7b0366f153284db0ad3347c457ea70136"}],"title":"nfsd: clear acl_access/acl_default after releasing them","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2025-21796","datePublished":"2025-02-27T02:18:32.191Z","dateReserved":"2024-12-29T08:45:45.768Z","dateUpdated":"2026-07-14T12:40:10.487Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2025-02-27 03:15:20","lastModifiedDate":"2026-07-14 13:17:23","problem_types":["CWE-416","CWE-416 CWE-416 Use After Free"],"metrics":{"cvssMetricV31":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2025-02-27T17:57:11.080279Z","id":"CVE-2025-21796","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.13","versionEndExcluding":"5.10.235","matchCriteriaId":"083BAD0B-AAB6-42E6-AC7B-963EBC5214F6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"5.15.179","matchCriteriaId":"C708062C-4E1B-465F-AE6D-C09C46400875"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.16","versionEndExcluding":"6.1.129","matchCriteriaId":"2DA5009C-C9B9-4A1D-9B96-78427E8F232C"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"6.6.79","matchCriteriaId":"B16AADE5-B2FD-4C14-B4E4-85E8EDAFE775"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.7","versionEndExcluding":"6.12.16","matchCriteriaId":"13C8DB18-FC60-425F-84E5-3EDDEC61B2FC"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13","versionEndExcluding":"6.13.4","matchCriteriaId":"2A2093ED-74A9-43F9-AC72-50030F374EA4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:*","matchCriteriaId":"186716B6-2B66-4BD0-852E-D48E71C0C85F"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:*","matchCriteriaId":"0D3E781C-403A-498F-9DA9-ECEE50F41E75"}]}]}]},"legacy_mitre":{"record":{"CveYear":"2025","CveId":"21796","Ordinal":"1","Title":"nfsd: clear acl_access/acl_default after releasing them","CVE":"CVE-2025-21796","Year":"2025"},"notes":[{"CveYear":"2025","CveId":"21796","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: clear acl_access/acl_default after releasing them\n\nIf getting acl_default fails, acl_access and acl_default will be released\nsimultaneously. However, acl_access will still retain a pointer pointing\nto the released posix_acl, which will trigger a WARNING in\nnfs3svc_release_getacl like this:\n\n------------[ cut here ]------------\nrefcount_t: underflow; use-after-free.\nWARNING: CPU: 26 PID: 3199 at lib/refcount.c:28\nrefcount_warn_saturate+0xb5/0x170\nModules linked in:\nCPU: 26 UID: 0 PID: 3199 Comm: nfsd Not tainted\n6.12.0-rc6-00079-g04ae226af01f-dirty #8\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS\n1.16.1-2.fc37 04/01/2014\nRIP: 0010:refcount_warn_saturate+0xb5/0x170\nCode: cc cc 0f b6 1d b3 20 a5 03 80 fb 01 0f 87 65 48 d8 00 83 e3 01 75\ne4 48 c7 c7 c0 3b 9b 85 c6 05 97 20 a5 03 01 e8 fb 3e 30 ff <0f> 0b eb\ncd 0f b6 1d 8a3\nRSP: 0018:ffffc90008637cd8 EFLAGS: 00010282\nRAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff83904fde\nRDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffff88871ed36380\nRBP: ffff888158beeb40 R08: 0000000000000001 R09: fffff520010c6f56\nR10: ffffc90008637ab7 R11: 0000000000000001 R12: 0000000000000001\nR13: ffff888140e77400 R14: ffff888140e77408 R15: ffffffff858b42c0\nFS:  0000000000000000(0000) GS:ffff88871ed00000(0000)\nknlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 0000562384d32158 CR3: 000000055cc6a000 CR4: 00000000000006f0\nDR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\nDR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\nCall Trace:\n <TASK>\n ? refcount_warn_saturate+0xb5/0x170\n ? __warn+0xa5/0x140\n ? refcount_warn_saturate+0xb5/0x170\n ? report_bug+0x1b1/0x1e0\n ? handle_bug+0x53/0xa0\n ? exc_invalid_op+0x17/0x40\n ? asm_exc_invalid_op+0x1a/0x20\n ? tick_nohz_tick_stopped+0x1e/0x40\n ? refcount_warn_saturate+0xb5/0x170\n ? refcount_warn_saturate+0xb5/0x170\n nfs3svc_release_getacl+0xc9/0xe0\n svc_process_common+0x5db/0xb60\n ? __pfx_svc_process_common+0x10/0x10\n ? __rcu_read_unlock+0x69/0xa0\n ? __pfx_nfsd_dispatch+0x10/0x10\n ? svc_xprt_received+0xa1/0x120\n ? xdr_init_decode+0x11d/0x190\n svc_process+0x2a7/0x330\n svc_handle_xprt+0x69d/0x940\n svc_recv+0x180/0x2d0\n nfsd+0x168/0x200\n ? __pfx_nfsd+0x10/0x10\n kthread+0x1a2/0x1e0\n ? kthread+0xf4/0x1e0\n ? __pfx_kthread+0x10/0x10\n ret_from_fork+0x34/0x60\n ? __pfx_kthread+0x10/0x10\n ret_from_fork_asm+0x1a/0x30\n </TASK>\nKernel panic - not syncing: kernel: panic_on_warn set ...\n\nClear acl_access/acl_default after posix_acl_release is called to prevent\nUAF from being triggered.","Type":"Description","Title":"nfsd: clear acl_access/acl_default after releasing them"}]}}}