CVE-2023-53559: ip_vti: fix potential slab-use-after-free in decode_session6

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-10-04 · updated 2026-08-04
Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: ip_vti: fix potential slab-use-after-free in decode_session6 When ip_vti device is set to the qdisc of the sfb type, the cb field of the sent skb may be modified during enqueuing. Then, slab-use-after-free may occur when ip_vti device sends IPv6 packets. As commit f855691975bb ("xfrm6: Fix the nexthdr offset in _decode_session6.") showed, xfrm_decode_session was originally intended only for the receive path. IP6CB(skb)->nhoff is not set during transmission. Therefore, set the cb field in the skb to 0 before sending packets.

Affected products

Linux kernel: from 3.19.1 before 4.14.324; from 4.15 before 4.19.293; from 4.20 before 5.4.255; from 5.5 before 5.10.192; from 5.11 before 5.15.128; from 5.16 before 6.1.47 — fixed in 4.14.324, 4.19.293, 5.10.192, 5.15.128, 5.4.255, 6.1.47

How to fix

Upgrade to a fixed version: Linux kernel 4.14.324, 4.19.293, 5.10.192, 5.15.128. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2023-53559 or the next vulnerability affects your stack