CVE-2026-64531
What it is
In the Linux kernel, the following vulnerability has been resolved: net: openvswitch: reject oversized nested action attrs Open vSwitch stores generated flow actions as nlattrs, whose nla_len field is u16. Commit a1e64addf3ff ("net: openvswitch: remove misbehaving actions length check") allowed the total sw_flow_actions stream to grow beyond 64 KiB, which is valid, but also removed the last guard preventing a generated nested action attribute from exceeding U16_MAX. An oversized generated container can thus be closed with a truncated nla_len. A later dump or teardown then walks a structurally different stream than the one that was validated. In particular, an oversized nested CLONE/CT action may cause subsequent bytes in the generated stream to be interpreted as independent actions. Keep the larger total-action-stream behavior, but make nested action close reject generated containers that do not fit in nla_len, and return the error through all callers. For recursive SAMPLE, CLONE, DEC_TTL, and CHECK_PKT_LEN builders, trim resource-owning action-list tails in reverse construction order before discarding failed wrappers, so resources copied into the rejected tails are released before the wrappers are removed. Most failed outer wrappers are discarded by truncating actions_len after child resources have been released. CHECK_PKT_LEN also trims its parent after branch resources are gone. SET/TUNNEL close failures unwind their known tun_dst ownership directly, and SET_TO_MASKED has no external ownership and truncates on close failure.
At a glance
- Exploitability
- Can be exploited locally on the machine with a low-privilege account. High risk of data exposure, data tampering, service disruption.
- Exploit odds
- 0.4% chance of exploitation in the next 30 days (EPSS).
- Fix
- No patch or advisory is linked yet. Look at mitigations or restrict exposure.
Timeline
- ReservedThe CVE id was reserved by its CNA
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 0.4% in the next 30 days (EPSS).
- Severity: 7.8 HIGH (CVSS).
- Fix: none linked yet, which raises it.
Details
- Published
- Last modified
- Exploit probability
- 0.4% · EPSS, next 30 days
- Weakness
- CWE-190 · Integer overflow
- Record status
- Awaiting Analysis
Attack profile CVSS 3.1 · 7.8
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2026-64531.md and follow it. Check whether this project is affected by CVE-2026-64531. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
References
- https://git.kernel.org/stable/c/1b41cbe05b184f8861712f0806cc0c4f5d8c6dfe
- https://git.kernel.org/stable/c/3f1f755366687d051174739fb99f7d560202f60b
- https://git.kernel.org/stable/c/ab855641241387db062a5e41d9ad6b8561542572
- https://git.kernel.org/stable/c/c66bd2626c2764f23764ff0f8277f44a9cfe8349
- https://git.kernel.org/stable/c/d573250d228401f707f4dbc09d11227a6215ee5f
- https://git.kernel.org/stable/c/dbd14f736be02cfe73049bd801af89becd1a0749
- https://git.kernel.org/stable/c/f1efff8858403191361a01269c6fe8dd7f55a385
- http://www.openwall.com/lists/oss-security/2026/07/28/8
- http://www.openwall.com/lists/oss-security/2026/07/31/17
- http://www.openwall.com/lists/oss-security/2026/08/01/1
- http://www.openwall.com/lists/oss-security/2026/08/01/3
- http://www.openwall.com/lists/oss-security/2026/08/22/1