CVE-2026-64440 staging: rtl8723bs: fix OOB write in HT_caps_handler()
A malicious access point can trigger an out-of-bounds write in the rtl8723bs Wi-Fi driver, potentially leading to code execution or privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-64440?
CVE-2026-64440 is a high-severity memory corruption vulnerability in Linux kernel, published on 25 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-787
Which versions are affected by CVE-2026-64440?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64440?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-64440 being exploited?
There is no known exploitation of CVE-2026-64440 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-64440, DEBIAN-CVE-2026-64440, GHSA-mgm7-8p4q-p28m, ROOT-OS-DEBIAN-12-CVE-2026-64440, ROOT-OS-UBUNTU-2204-CVE-2026-64440, UBUNTU-CVE-2026-64440.