SB20261029184 - Use-after-free in Linux kernel ipv4

Description

This security bulletin contains information about 1 vulnerability.

1) Use-after-free (CVE-ID: CVE-2026-99139)

CWE-ID: CWE-416 - Use After Free

CVSSv4: 5.8 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows a local user to potentially cause a denial of service or disclose kernel memory.

The vulnerability exists due to use-after-free in the Linux kernel's do_tcp_getsockopt() function when reading the TCP_CONGESTION algorithm name without RCU read-side protection. A local user can race getsockopt(TCP_CONGESTION) with setsockopt(TCP_CONGESTION), causing dynamically allocated BPF struct_ops memory to be freed while its name is being copied to user space, to potentially crash the kernel or disclose kernel memory.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/5271b79b7ad68dcb222e893773f92bdabf7750f3
• https://git.kernel.org/stable/c/a8e45471afa230c1431c26c8e99ec24377e3b514
• https://git.kernel.org/stable/c/c1804ef016392dd91267d2207ee43b1de34302ca