SB2026062650 - Use-after-free in Linux kernel l2tp

Description

This security bulletin contains information about 1 vulnerability.

1) Use-after-free (CVE-ID: CVE-2026-53262)

CWE-ID: CWE-416 - Use After Free

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a local user to cause a denial of service or execute arbitrary code.

The vulnerability exists due to use-after-free in pppol2tp_ioctl() when processing ioctl requests while a concurrent socket close frees the associated l2tp_session after a controllable sleep during copy_from_user(). A local user can trigger a userfaultfd-assisted page fault sleep and race a socket close to dereference a stale session pointer to cause a denial of service or execute arbitrary code.

Exploitation requires local access to issue the ioctl and induce the race condition.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/62f327e287cf7b595ae3f73ba72f5cd2a9e9f39f
• https://git.kernel.org/stable/c/78cdfdca88cbf731a92f3b9ee5427c633dd94e28
• https://git.kernel.org/stable/c/a213a8950414c684999dcf03edeea6c46ede172e
• https://git.kernel.org/stable/c/e251d4cdfc725c9e7d686161e3b775a0e7d95053