Use-after-free in Linux kernel nfsd

1) Use-after-free

EUVDB-ID: #VU104953

Risk: Low

CVSSv4.0: 5.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2025-21796

CWE-ID: CWE-416 - Use After Free

Exploit availability: No

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a use-after-free error within the posix_acl_release() function in fs/nfsd/nfs3acl.c, within the posix_acl_release() function in fs/nfsd/nfs2acl.c. A local user can escalate privileges on the system.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Linux kernel: All versions

CPE2.3

• cpe:2.3:o:linux_foundation:linux_kernel:*:*:*:*:*:*:*:*

External links

https://git.kernel.org/stable/c/1fd94884174bd20beb1773990fd3b1aa877688d9
https://git.kernel.org/stable/c/2e59b2b68782519560b3d6a41dd66a3d01a01cd3
https://git.kernel.org/stable/c/55d947315fb5f67a35e4e1d3e01bb886b9c6decf
https://git.kernel.org/stable/c/7faf14a7b0366f153284db0ad3347c457ea70136
https://git.kernel.org/stable/c/f8d871523142f7895f250a856f8c4a4181614510

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.