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Linux Kernel mt7921 CVE-2026-53317

| EUVDEUVD-2026-39852 MEDIUM
2026-06-26 Linux GHSA-86cw-5chj-gj42
Denial Of Service Linux Red Hat Mediatek Suse
5.5
CVSS 3.1 · NVD
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Severity by source

NVD PRIMARY
5.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
vuln.today AI
5.5 MEDIUM

Local vector and low privilege required to control hostapd configuration; no confidentiality or integrity impact, only firmware DoS.

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.0 AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
MEDIUM
qualitative
Red Hat
5.5 MEDIUM
qualitative

Primary rating from NVD.

CVSS VectorNVD

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

5
Analysis Generated
Jul 06, 2026 - 20:43 vuln.today
CVSS changed
Jul 06, 2026 - 20:22 NVD
5.5 (MEDIUM)
Patch available
Jun 26, 2026 - 21:02 EUVD
CVE Published
Jun 26, 2026 - 19:41 nvd
MEDIUM 5.5
CVE Published
Jun 26, 2026 - 19:41 cve.org
UNKNOWN (no severity yet)

DescriptionNVD

In the Linux kernel, the following vulnerability has been resolved:

wifi: mt76: mt7921: Place upper limit on station AID

Any station configured with an AID over 20 causes a firmware crash. This situation occurred in our testing using an AP interface on 7922 hardware, with a modified hostapd, sourced from Mediatek's OpenWRT feeds.

In stock hostapd, station AIDs begin counting at 1, and this configuration is prevented with an upper limit on associated stations. However, the modified hostapd began allocation at 65, which caused the firmware to crash. This fix does not allow these AIDs to work, but will prevent the firmware crash.

This crash was only seen on IFTYPE_AP interfaces, and the fix does not appear to have an effect on IFTYPE_STATION behavior.

AnalysisAI

Firmware crash in the Linux kernel's mt76/mt7921 WiFi driver allows a local low-privileged user to cause denial of service by triggering station Association ID (AID) values above the firmware's undocumented limit of 20. Affected hardware includes Mediatek mt7922 chipsets operating in AP mode (IFTYPE_AP). Exploitation requires running a non-standard hostapd configuration that allocates AIDs starting at 65 or higher - stock hostapd is not affected. No public exploit has been identified and EPSS is 0.16% (5th percentile), indicating very low exploitation likelihood.

Technical ContextAI

The mt76 driver family supports Mediatek 802.11 WiFi chipsets in the Linux kernel. The mt7921 sub-driver handles the mt7921 and mt7922 chips. When operating in IFTYPE_AP mode, the driver passes station Association IDs (AIDs) to the firmware, which appear to have an undocumented upper bound of 20. The stock hostapd daemon assigns AIDs starting at 1 and enforces its own upper bound via max_sta configuration, which prevents this condition in typical deployments. The Mediatek OpenWRT-derived modified hostapd starts AID allocation at 65, which bypasses the stock safeguard and causes the firmware to crash when it receives an AID it cannot handle. The root cause is missing bounds validation in the driver - there is no CWE assigned, but the class corresponds to improper input validation (CWE-20) or improper array index validation (CWE-129) before passing host-configured values to firmware. The CPE cpe:2.3:a:linux:linux:* confirms multiple stable kernel branches are affected, with the regression introduced at commit 5c14a5f944b91371961548b1907802f74a4d2e5c.

RemediationAI

The primary fix is to upgrade to a patched kernel: Linux 6.12.91, 6.18.33, 7.0.10, or 7.1, which add an upper bound check on station AID values in the mt7921 driver before passing them to firmware. Patch commits are linked from the kernel stable tree (https://git.kernel.org/stable/c/35835ff71e6e618155578b8e3905597edd5f601c and related). For systems that cannot immediately upgrade, the effective workaround is to replace or revert any modified hostapd binary sourced from Mediatek's OpenWRT feeds with stock hostapd, which allocates AIDs starting at 1 and keeps them below the firmware limit. Alternatively, restricting the AP's maximum associated stations to a value that keeps AID assignments below 20 via hostapd's max_num_sta parameter prevents the condition. Note that this vulnerability only manifests in AP mode - if the device operates exclusively in station mode, no mitigation is required.

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Affected
SUSE Linux Enterprise High Availability Extension 16.0 Not-Affected

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CVE-2026-53317 vulnerability details – vuln.today
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