> CVE-2025-21796 [HIGH]

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PUBLISHED
2025-02-27 03:15
MODIFIED
2025-03-21 15:42
CVSS_SCORE V3
7.8
EPSS (Prob. Exploit)
0.67%
Top 47.6%
DATA SOURCES:
NVD 🔗 2025-10-18 RED HAT 🔗 2025-10-18 CVE PROJECT 🔗 2026-01-19 FIRST EPSS 🔗 2026-11-08 OSV 🔗 2026-11-08 MSRC 🔗 2026-02-01

> DESCRIPTION

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: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> ? refcount_warn_saturate+0xb5/0x170 ? __warn+0xa5/0x140 ? refcount_warn_saturate+0xb5/0x170 ? report_bug+0x1b1/0x1e0 ? handle_bug+0x53/0xa0 ? exc_invalid_op+0x17/0x40 ? asm_exc_invalid_op+0x1a/0x20 ? tick_nohz_tick_stopped+0x1e/0x40 ? refcount_warn_saturate+0xb5/0x170 ? refcount_warn_saturate+0xb5/0x170 nfs3svc_release_getacl+0xc9/0xe0 svc_process_common+0x5db/0xb60 ? __pfx_svc_process_common+0x10/0x10 ? __rcu_read_unlock+0x69/0xa0 ? __pfx_nfsd_dispatch+0x10/0x10 ? svc_xprt_received+0xa1/0x120 ? xdr_init_decode+0x11d/0x190 svc_process+0x2a7/0x330 svc_handle_xprt+0x69d/0x940 svc_recv+0x180/0x2d0 nfsd+0x168/0x200 ? __pfx_nfsd+0x10/0x10 kthread+0x1a2/0x1e0 ? kthread+0xf4/0x1e0 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x34/0x60 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 </TASK> Kernel panic - not syncing: kernel: panic_on_warn set ... Clear acl_access/acl_default after posix_acl_release is called to prevent UAF from being triggered.

> AFFECTED_PRODUCTS

Linux - Linux Kernel
>= 2.6.13 < 5.10.235
Linux - Linux Kernel
>= 5.11 < 5.15.179
Linux - Linux Kernel
>= 5.16 < 6.1.129
Linux - Linux Kernel
>= 6.2 < 6.6.79
Linux - Linux Kernel
>= 6.7 < 6.12.16
Linux - Linux Kernel
>= 6.13 < 6.13.4
Linux - Linux Kernel
Version: 6.14

> CVSS V3 METRICS

CVSS_VECTOR
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

> MÉTRIQUES CVSS DÉTAILLÉES

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Métrique Valeur Interprétation
AV (Vecteur d'Attaque)
Attack Vector
Local (L)
Exploit nécessite un accès local au système
AC (Complexité d'Attaque)
Attack Complexity
Low (L)
Peu de conditions requises pour exploiter
PR (Privilèges Requis)
Privileges Required
Low (L)
Authentifié avec compte utilisateur basique
UI (Interaction Utilisateur)
User Interaction
None (N)
Aucune interaction utilisateur nécessaire
S (Périmètre)
Scope
Unchanged (U)
Impact reste dans le périmètre du composant compromis
C (Impact Confidentialité)
Confidentiality Impact
High (H)
Divulgation totale d'informations
I (Impact Intégrité)
Integrity Impact
High (H)
Modification totale des données possible
A (Impact Disponibilité)
Availability Impact
High (H)
Interruption totale du service possible

> RÉSUMÉ DES IMPACTS

Confidentialité
High
Divulgation totale d'informations
Intégrité
High
Modification totale des données possible
Disponibilité
High
Interruption totale du service possible

> RED HAT SECURITY ADVISORIES

Red Hat Security Advisory: kernel security update
An update for kernel is now available for Red Hat Enterprise Linux 9. Red Hat Product Security has rated this update as having a security impact of Moderate. A Common Vulnerability Scoring System (CV...
Red Hat Security Advisory: kernel security update
An update for kernel is now available for Red Hat Enterprise Linux 10. Red Hat Product Security has rated this update as having a security impact of Moderate. A Common Vulnerability Scoring System (C...

> RED HAT SEVERITY ASSESSMENT

THREAT SEVERITY
Moderate

> OSV (GOOGLE OPEN SOURCE VULNERABILITIES)

nfsd: clear acl_access/acl_default after releasing them

AFFECTED PACKAGES:
Unknown / Unknown
Linux / Kernel

> HISTORIQUE DES MODIFICATIONS

Première apparition
27/02/2025 03:15
Source: NVD
📊 ENRICHISSEMENT 18/10/2025 15:01
CVEPROJECT
Champ modifié: CVE Project
Ancienne valeur:
Non
Nouvelle valeur:
Oui
📊 ENRICHISSEMENT 18/10/2025 12:20
REDHAT
Champ modifié: Sévérité Red Hat
Ancienne valeur:
N/A
Nouvelle valeur:
{ "threat_severity": "Moderate", "severity_scale": null }
📊 ENRICHISSEMENT 18/10/2025 12:20
REDHAT
Champ modifié: Red Hat
Ancienne valeur:
Non
Nouvelle valeur:
Oui
Total des modifications: 3 Dernière mise à jour: 1 year ago
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