SB20261022168 - Integer underflow in Linux kernel skb_pointer_if_linear() in include/linux/skbuff.h, used by skb-backed BPF dynptr code

Description

This security bulletin contains information about 1 vulnerability.

1) Integer underflow (CVE-ID: CVE-2026-98591)

CWE-ID: CWE-191 - Integer underflow

CVSSv4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows a local user to cause invalid kernel memory access, potentially resulting in a denial of service.

The vulnerability exists due to an unsigned integer underflow in skb_pointer_if_linear() when checking whether a memory range used by an skb-backed BPF dynptr lies within the skb linear area. A local user can trigger the bounds check with an out-of-bounds offset to cause it to incorrectly accept the range and return an invalid backing pointer, potentially resulting in a denial of service when that pointer is accessed.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/1196903a27cac5c929c7517e987a8d159f20c5e5
• https://git.kernel.org/stable/c/1b923538598be768e9f2f258a77a083d00e0c78b
• https://git.kernel.org/stable/c/37877a24758068742fef687a7cf5362360dde1d1
• https://git.kernel.org/stable/c/39ffceaddb10753eac12785dba6ac0673860b4ac
• https://git.kernel.org/stable/c/ed6eec97b534979dcf28b40c389cee57bd6561d4