CVE-2025-21796

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Source
https://cve.org/CVERecord?id=CVE-2025-21796
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-21796.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2025-21796
Downstream
Related
Published
2025-02-27T02:18:32.191Z
Modified
2026-05-07T04:16:31.311284Z
Severity
  • 7.8 (High) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
Summary
nfsd: clear acl_access/acl_default after releasing them
Details

In the Linux kernel, the following vulnerability has been resolved:

nfsd: clear aclaccess/acldefault after releasing them

If getting acldefault fails, aclaccess and acldefault will be released simultaneously. However, aclaccess will still retain a pointer pointing to the released posixacl, which will trigger a WARNING in nfs3svcrelease_getacl like this:

------------[ cut here ]------------ refcountt: underflow; use-after-free. WARNING: CPU: 26 PID: 3199 at lib/refcount.c:28 refcountwarnsaturate+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:refcountwarnsaturate+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: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> ? refcountwarn_saturate+0xb5/0x170 ? __warn+0xa5/0x140 ? refcountwarnsaturate+0xb5/0x170 ? reportbug+0x1b1/0x1e0 ? handlebug+0x53/0xa0 ? excinvalidop+0x17/0x40 ? asmexcinvalidop+0x1a/0x20 ? ticknohztickstopped+0x1e/0x40 ? refcountwarnsaturate+0xb5/0x170 ? refcountwarnsaturate+0xb5/0x170 nfs3svcreleasegetacl+0xc9/0xe0 svcprocesscommon+0x5db/0xb60 ? __pfxsvcprocess_common+0x10/0x10 ? __rcureadunlock+0x69/0xa0 ? __pfxnfsddispatch+0x10/0x10 ? svcxprtreceived+0xa1/0x120 ? xdrinitdecode+0x11d/0x190 svcprocess+0x2a7/0x330 svchandlexprt+0x69d/0x940 svcrecv+0x180/0x2d0 nfsd+0x168/0x200 ? __pfx_nfsd+0x10/0x10 kthread+0x1a2/0x1e0 ? kthread+0xf4/0x1e0 ? __pfxkthread+0x10/0x10 retfrom_fork+0x34/0x60 ? __pfxkthread+0x10/0x10 retfromforkasm+0x1a/0x30 </TASK> Kernel panic - not syncing: kernel: paniconwarn set ...

Clear aclaccess/acldefault after posixaclrelease is called to prevent UAF from being triggered.

Database specific 
{
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21796.json",
    "cna_assigner": "Linux"
}
References

Affected packages

Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

Affected ranges

Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
a257cdd0e2179630d3201c32ba14d7fcb3c3a055
Fixed
8a1737ae42c928384ab6447f6ee1a882510e85fa
Fixed
6f7cfee1a316891890c505563aa54f3476db52fd
Fixed
2e59b2b68782519560b3d6a41dd66a3d01a01cd3
Fixed
55d947315fb5f67a35e4e1d3e01bb886b9c6decf
Fixed
f8d871523142f7895f250a856f8c4a4181614510
Fixed
1fd94884174bd20beb1773990fd3b1aa877688d9
Fixed
7faf14a7b0366f153284db0ad3347c457ea70136

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-21796.json"

Linux / Kernel

Package

Name
Kernel

Affected ranges

Type
ECOSYSTEM
Events
Introduced
2.6.13
Fixed
5.10.235
Type
ECOSYSTEM
Events
Introduced
5.11.0
Fixed
5.15.179
Type
ECOSYSTEM
Events
Introduced
5.16.0
Fixed
6.1.129
Type
ECOSYSTEM
Events
Introduced
6.2.0
Fixed
6.6.79
Type
ECOSYSTEM
Events
Introduced
6.7.0
Fixed
6.12.16
Type
ECOSYSTEM
Events
Introduced
6.13.0
Fixed
6.13.4

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-21796.json"