# CVE-2026-64531 — Linux

> As of 2026-08-22, CVE-2026-64531 is a HIGH-severity vulnerability in Linux, CVSS v3.1 7.8, EPSS 0.5% (44.6th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-64531, most recently “OVSWrap (CVE-2026-64531): Linux kernel Open vSwitch datapath 16-bit nla_len wraparound local privilege escalation with public PoC targeting ~800 x86-64 kernel builds”.

**Last updated:** 2026-08-22

## What is CVE-2026-64531?

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.

Its CVSS v3 base vector states that the flaw requires local access to the host, needs low-privilege credentials, needs no user interaction, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 93 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 7.8 — HIGH (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **EPSS (FIRST):** 0.5% probability of exploitation in the next 30 days, higher than 44.6% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 7.7/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-07-27, last modified 2026-08-22

## Is CVE-2026-64531 being exploited?

Weaponised exploit code for CVE-2026-64531 is publicly available. 5 public proof-of-concept repositories are tracked for this identifier. It currently carries a trending score of 35 in the Threadlinqs vulnerability feed.

- [HackSpeak/CVE-2026-64531](https://github.com/HackSpeak/CVE-2026-64531) (github)
- [mahfuzreham/OVSwrap-CVE-2026-64531-Mitigation-Tool](https://github.com/mahfuzreham/OVSwrap-CVE-2026-64531-Mitigation-Tool) (github)
- [0xBlackash/CVE-2026-64531](https://github.com/0xBlackash/CVE-2026-64531) (github)
- [suominen/ovswrap](https://github.com/suominen/ovswrap) (github)
- [trickest/cve](https://github.com/trickest/cve/blob/main/2026/CVE-2026-64531.md) (trickest)

## Affected products and versions

- [Linux](https://intel.threadlinqs.com/vendors/linux): Linux

## How to fix CVE-2026-64531

No vendor patch reference has been recorded for CVE-2026-64531 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-64531

1 tracked threat in the Threadlinqs corpus references CVE-2026-64531, either in the campaign’s CVE list or as an indicator on the campaign record.

- [OVSWrap (CVE-2026-64531): Linux kernel Open vSwitch datapath 16-bit nla_len wraparound local privilege escalation with public PoC targeting ~800 x86-64 kernel builds](https://intel.threadlinqs.com/threat/TL-2026-1887) — HIGH · 2026-08-05

## Sources

Enriched from CVE.org, FIRST EPSS, GitHub Security Advisories, public proof-of-concept repositories. Last verified by Threadlinqs on 2026-10-10.

**Other references**

- [git.kernel.org](https://git.kernel.org/stable/c/ab855641241387db062a5e41d9ad6b8561542572)
- [git.kernel.org (c66bd2626c2764f23764ff0f8277f44a9cfe8349)](https://git.kernel.org/stable/c/c66bd2626c2764f23764ff0f8277f44a9cfe8349)
- [git.kernel.org (d573250d228401f707f4dbc09d11227a6215ee5f)](https://git.kernel.org/stable/c/d573250d228401f707f4dbc09d11227a6215ee5f)
- [git.kernel.org (f1efff8858403191361a01269c6fe8dd7f55a385)](https://git.kernel.org/stable/c/f1efff8858403191361a01269c6fe8dd7f55a385)
- [git.kernel.org (dbd14f736be02cfe73049bd801af89becd1a0749)](https://git.kernel.org/stable/c/dbd14f736be02cfe73049bd801af89becd1a0749)

_Showing 5 of 7 recorded references._

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-64531
Full detection coverage and IOCs for threats exploiting CVE-2026-64531 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp