CVE-2026-23152 Overview
A vulnerability has been identified in the Linux kernel's mac80211 WiFi subsystem involving incorrect parsing of TID-To-Link Mapping (TTLM) elements when a default link map is used. The vulnerability occurs because TTLM elements do not contain a link mapping presence indicator when default mapping is used, and the parsing logic fails to account for this scenario. This results in mac80211 incorrectly parsing frames and reading one byte beyond the end of the element, constituting an out-of-bounds read condition.
Critical Impact
Out-of-bounds memory read in the Linux kernel WiFi stack may lead to information disclosure or system instability when processing malformed TTLM frames.
Affected Products
- Linux kernel with mac80211 WiFi subsystem
- Systems using WiFi with TID-To-Link Mapping support
- WiFi-enabled Linux devices with Multi-Link Operation (MLO) capabilities
Discovery Timeline
- 2026-02-14 - CVE CVE-2026-23152 published to NVD
- 2026-02-18 - Last updated in NVD database
Technical Details for CVE-2026-23152
Vulnerability Analysis
The vulnerability resides in the mac80211 subsystem of the Linux kernel, specifically in the code responsible for decoding TID-To-Link Mapping (TTLM) elements used in WiFi 7 (802.11be) Multi-Link Operation. TTLM is a mechanism that allows mapping traffic identifiers (TIDs) to specific links in a multi-link setup.
When an access point uses a default link mapping, the TTLM element structure differs from explicit mappings—it does not include a link mapping presence indicator. The vulnerable parsing code fails to properly handle this case, proceeding to read data that is not present in the element. This causes a one-byte out-of-bounds read beyond the element boundary.
While access points should not explicitly advertise TTLM with default mapping (since the absence of the element implies default mapping), the parsing code must still handle malformed or unexpected frames gracefully to prevent memory safety violations.
Root Cause
The root cause is improper input validation in the TTLM element parsing routine within mac80211. The code does not verify whether the element contains a link mapping presence indicator before attempting to parse it. When a default mapping is indicated, the parsing should be skipped entirely, but instead the code continues and accesses memory beyond the element's bounds.
Attack Vector
An attacker could craft malicious WiFi frames containing TTLM elements with default mapping indicators to trigger the out-of-bounds read. This would require the attacker to be within WiFi range of the target system. The attack could potentially:
- Cause information disclosure by reading adjacent kernel memory
- Trigger system instability or crashes depending on the memory contents accessed
- Potentially be chained with other vulnerabilities for more severe exploitation
The vulnerability is triggered during frame parsing, which occurs when processing management frames from access points or other WiFi devices.
Detection Methods for CVE-2026-23152
Indicators of Compromise
- Unexpected kernel warnings or oops messages related to mac80211 or WiFi frame parsing
- System crashes or instability when connecting to or receiving frames from WiFi networks
- Anomalous WiFi management frames with malformed TTLM elements detected in network captures
Detection Strategies
- Monitor kernel logs for warnings or errors originating from mac80211 or net/mac80211/ code paths
- Implement wireless intrusion detection systems (WIDS) to identify malformed 802.11be management frames
- Deploy endpoint detection solutions capable of monitoring kernel behavior for out-of-bounds memory access attempts
Monitoring Recommendations
- Enable kernel address sanitizer (KASAN) on development or testing systems to detect out-of-bounds memory accesses
- Monitor system logs for WiFi subsystem errors using journalctl -k | grep -i mac80211
- Configure alerting for unexpected kernel panics or oops events on WiFi-enabled systems
How to Mitigate CVE-2026-23152
Immediate Actions Required
- Apply the latest Linux kernel security updates containing the fix for this vulnerability
- Review kernel version and ensure patches from the referenced commits are applied
- Consider temporarily disabling WiFi on critical systems until patching is complete
Patch Information
The vulnerability has been resolved in the Linux kernel. The fix ensures that TTLM parsing is properly skipped when a default link mapping is used, preventing the out-of-bounds read.
Patches are available through the official kernel repositories:
Workarounds
- Disable WiFi functionality if not required until the system can be patched
- Use wired network connections as an alternative to WiFi on affected systems
- Implement network segmentation to limit exposure of vulnerable systems to untrusted WiFi networks
# Temporarily disable WiFi interface until patching is complete
ip link set wlan0 down
# Or using rfkill
rfkill block wifi
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
