Critical

nfsd: clear acl_access/acl_default after releasing them

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: nfsd: clear acl_access/acl_default after releasing them If getting acl_default fails, acl_access and acl_default will be released simultaneously. However, acl_access will still retain a pointer pointing to the released posix_acl, which will trigger a WARNING in nfs3svc_release_getacl like this: ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 26 PID: 3199 at lib/refcount.c:28 refcount_warn_saturate+0xb5/0x170 Modules linked in: CPU: 26 UID: 0 PID: 3199 Comm: nfsd Not tainted 6.12.0-rc6-00079-g04ae226af01f-dirty #8 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 RIP: 0010:refcount_warn_saturate+0xb5/0x170 Code: cc cc 0f b6 1d b3 20 a5 03 80 fb 01 0f 87 65 48 d8 00 83 e3 01 75 e4 48 c7 c7 c0 3b 9b 85 c6 05 97 20 a5 03 01 e8 fb 3e 30 ff <0f> 0b eb cd 0f b6 1d 8a3 RSP: 0018:ffffc90008637cd8 EFLAGS: 00010282 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff83904fde RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffff88871ed36380 RBP: ffff888158beeb40 R08: 0000000000000001 R09: fffff520010c6f56 R10: ffffc90008637ab7 R11: 0000000000000001 R12: 0000000000000001 R13: ffff888140e77400 R14: ffff888140e77408 R15: ffffffff858b42c0 FS: 0000000000000000(0000) GS:ffff88871ed00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000562384d32158 CR3: 000000055cc6a000 CR4: 00000000000006f0 DR0: 0000000000000

Announced 27 Feb 2025Group revision 1

Original source ↗

CVE-2025-21796

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2025-21796

Linux

Source reference: /containers/cna/affected/0/product

Affected versions: Not stated in this record
Fixed versions: Not stated in this record
Prerequisites: Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions: Not stated in this record
Fixed versions: Not stated in this record
Prerequisites: Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "a257cdd0e2179630d3201c32ba14d7fcb3c3a055",
        "lessThan": "8a1737ae42c928384ab6447f6ee1a882510e85fa",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "a257cdd0e2179630d3201c32ba14d7fcb3c3a055",
        "lessThan": "6f7cfee1a316891890c505563aa54f3476db52fd",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "a257cdd0e2179630d3201c32ba14d7fcb3c3a055",
        "lessThan": "2e59b2b68782519560b3d6a41dd66a3d01a01cd3",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "a257cdd0e2179630d3201c32ba14d7fcb3c3a055",
        "lessThan": "55d947315fb5f67a35e4e1d3e01bb886b9c6decf",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "a257cdd0e2179630d3201c32ba14d7fcb3c3a055",
        "lessThan": "f8d871523142f7895f250a856f8c4a4181614510",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "a257cdd0e2179630d3201c32ba14d7fcb3c3a055",
        "lessThan": "1fd94884174bd20beb1773990fd3b1aa877688d9",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "a257cdd0e2179630d3201c32ba14d7fcb3c3a055",
        "lessThan": "7faf14a7b0366f153284db0ad3347c457ea70136",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "fs/nfsd/nfs2acl.c",
      "fs/nfsd/nfs3acl.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "2.6.13"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "2.6.13",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.235",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.179",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.129",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.79",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.16",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.13.4",
        "versionType": "semver",
        "lessThanOrEqual": "6.13.*"
      },
      {
        "status": "unaffected",
        "version": "6.14",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "fs/nfsd/nfs2acl.c",
      "fs/nfsd/nfs3acl.c"
    ],
    "defaultStatus": "affected"
  }
]

Related CVEs: CVE-2025-21796
Source reference: /cveMetadata/cveId

Publisher severity

critical

Source reference: /containers/cna/metrics

Event: #26948 · Revision 1
Added to Heist Feed: Sun, 25 Oct 2026 07:17:49 GMT
Publisher date: Thu, 27 Feb 2025 02:18:32 GMT

Read the original announcement

Revision history

25 Oct 2026CVE-2025-21796 · Revision 1Source updated