# CVE-2023-53559: ip\_vti: fix potential slab-use-after-free in decode\_session6

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2025-10-04 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 3.19

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
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## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/82fb41c5de243e7dfa90f32ca58e35adaff56c1d
- https://git.kernel.org/stable/c/7dfe23659f3677c08a60a0056cda2d91a79c15ca
- https://git.kernel.org/stable/c/d34c30442d5e53a33cde79ca163320dbe2432cbd
- https://git.kernel.org/stable/c/0b4d69539fdea138af2befe08893850c89248068
- https://git.kernel.org/stable/c/e1e04cc2ef2c0c0866c19f5627149a76c2baae32
- https://git.kernel.org/stable/c/2b05bf5dc437f7891dd409a3eaf5058459391c7a
- https://git.kernel.org/stable/c/78e397a43e1c47321a4679cc49a6c4530bf820b9
- https://git.kernel.org/stable/c/6018a266279b1a75143c7c0804dd08a5fc4c3e0b

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