#VU103511 Use-after-free in Linux kernel - CVE-2025-21671

Vulnerability identifier: #VU103511

Vulnerability 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-2025-21671

CWE-ID: CWE-416

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Linux kernel
Operating systems & Components / Operating system

Vendor: Linux Foundation

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 zram_meta_alloc() function in drivers/block/zram/zram_drv.c. A local user can escalate privileges on the system.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Linux kernel: All versions

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External links
https://git.kernel.org/stable/c/212fe1c0df4a150fb6298db2cfff267ceaba5402
https://git.kernel.org/stable/c/571d3f6045cd3a6d9f6aec33b678f3ffe97582ef
https://git.kernel.org/stable/c/902ef8f16d5ca77edc77c30656be54186c1e99b7
https://git.kernel.org/stable/c/fe3de867f94819ba0f28e035c0b0182150147d95

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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.