CVE-2026-64531: net: openvswitch: reject oversized nested action attrs
CVE-2026-64531 is a vulnerability in net: openvswitch: reject oversized nested action attrs, rated Moderate by Microsoft, with a CVSS 3.1 base score of 4.4 (Medium). An attacker can exploit it by an attacker with local access, with low privileges and without user interaction. Microsoft has not reported exploitation in the wild. The EPSS model estimates a 0.44% probability of exploitation activity in the next 30 days, higher than 39% of all scored vulnerabilities. Microsoft released the fix on 6 August 2026, outside Patch Tuesday. It affects 1 product in 1 product family (Open Source Software).
Key facts
- CVE ID
- CVE-2026-64531
- Severity
- Medium CVSS 4.4
- Microsoft severity
- Moderate
- Exploited in the wild
- No
- Publicly disclosed
- No
- Weakness
- CWE-190
- EPSS
- 0.44% (percentile 39%)
- CISA KEV
- Not listed
- Released
- Last updated
- Patch Tuesday
- July 2026 Patch Tuesday
- Product families
- Open Source Software
CVSS score and vector
Microsoft scores CVE-2026-64531 at 4.4 (temporal 4.4) using CVSS 3.1. Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
| Metric | Value |
|---|---|
| Attack vector | Local |
| Attack complexity | Low |
| Privileges required | Low |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality impact | None |
| Integrity impact | Low |
| Availability impact | Low |
NVD scores it 7.8 (HIGH) with CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
Affected products (1)
Open Source Software
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| azl3 kernel 6.6.144.1-1 on Azure Linux 3.0 | CBL-Mariner Releases | Security Update | 6.6.145.2-1 | No |
Exploitation and detection
Detection and weaponization
Weaponization maturity: Exploit.
Proof-of-concept repositories (4)
- suominen/ovswrap
- mahfuzreham/OVSwrap-CVE-2026-64531-Mitigation-Tool · 3 stars
- ashrafzaryouh/CVE-2026-64531 · 2 stars
- HackSpeak/CVE-2026-64531 · 11 stars
NIST NVD data
- NVD status
- Analyzed
- NVD CVSS
- 7.8 (HIGH)
- NVD weakness
- CWE-190
- Published to NVD
- NVD last modified
Affected configurations (CPE)
| Product | Vulnerable versions |
|---|---|
| linux kernel | from 5.15.180, before 5.15.212 |
| linux kernel | from 6.1.132, before 6.1.178 |
| linux kernel | from 6.6.84, before 6.6.145 |
| linux kernel | from 6.12.20, before 6.12.97 |
| linux kernel | from 6.13.8, before 6.14 |
| linux kernel | from 6.14.1, before 6.18.40 |
| linux kernel | from 6.19, before 7.1.5 |
| linux kernel 6.14 | all listed versions |
| linux kernel 6.14 | all listed versions |
| linux kernel 7.2 | all listed versions |
| linux kernel 7.2 | all listed versions |
| linux kernel 7.2 | all listed versions |
References
- https://git.kernel.org/stable/c/1b41cbe05b184f8861712f0806cc0c4f5d8c6dfe (Patch)
- https://git.kernel.org/stable/c/3f1f755366687d051174739fb99f7d560202f60b (Patch)
- https://git.kernel.org/stable/c/ab855641241387db062a5e41d9ad6b8561542572 (Patch)
- https://git.kernel.org/stable/c/c66bd2626c2764f23764ff0f8277f44a9cfe8349 (Patch)
- https://git.kernel.org/stable/c/d573250d228401f707f4dbc09d11227a6215ee5f (Patch)
- https://git.kernel.org/stable/c/dbd14f736be02cfe73049bd801af89becd1a0749 (Patch)
- https://git.kernel.org/stable/c/f1efff8858403191361a01269c6fe8dd7f55a385 (Patch)
- http://www.openwall.com/lists/oss-security/2026/07/28/8 (Mailing List)
- http://www.openwall.com/lists/oss-security/2026/07/31/17 (Mailing List)
- http://www.openwall.com/lists/oss-security/2026/08/01/1 (Mailing List)
- http://www.openwall.com/lists/oss-security/2026/08/01/3 (Mailing List)
- http://www.openwall.com/lists/oss-security/2026/08/22/1 (Mailing List)
Revision history
| Version | Date | Description |
|---|---|---|
| 1.0 | Information published. |