CVE-2026-64440: staging: rtl8723bs: fix OOB write in HT_caps_handler()
In the Linux kernel, the following vulnerability has been resolved:
staging: rtl8723bs: fix OOB write in HTcapshandler()
HTcapshandler() iterates pIE->length bytes and writes into HTcaps.u.HTcap[], which is a fixed 26-byte array (sizeof struct HTcapselement). 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 mlmeextinfo.
Truncate the iteration count to the size of HTcaps.u.HTcap 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->HTcapsenable = 1 assignment that precedes the loop, silently disabling HT mode for APs that append extra bytes to the HT Capabilities IE.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Linux kernel (rtl8723bs)to a version that resolves this vulnerability.Patch rtl8723bs: fix OOB write in HT_caps_handler() - Configuration
In the HT_caps_handler() loop, truncate the iteration count to the size of HT_caps.u.HT_cap using the umin() logic so that data from a longer-than-expected HT Capabilities IE is silently ignored and out-of-bounds writes are prevented.
HT_caps_handler() (rtl8723bs) Truncate iteration count when iterating over pIE->length for HT_caps.u.HT_cap = sizeof(HT_caps.u.HT_cap) (HT_caps_element)
Event History
Frequently Asked Questions
What is the severity of CVE-2026-64440?
CVE-2026-64440 has a severity rating of high with a CVSS score of 8.1.
How does CVE-2026-64440 impact system security?
CVE-2026-64440 can lead to out-of-bounds write vulnerabilities, potentially allowing an attacker to exploit the system.
How do I fix CVE-2026-64440?
To fix CVE-2026-64440, update your Linux kernel to the latest version that includes the patch for this vulnerability.
Which software is affected by CVE-2026-64440?
CVE-2026-64440 affects certain versions of the Linux kernel that utilize the rtl8723bs driver.
When was CVE-2026-64440 published?
CVE-2026-64440 was published on July 25, 2026.