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NVD / CVE Program· CNA Linux

CVE-2026-64531: net: openvswitch: reject oversized nested action attrs

Noroxi assessment

Priority: Monitor (action score 31/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.38% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 1b41cbe05b184f8861712f0806cc0c4f5d8c6dfe, 3f1f755366687d051174739fb99f7d560202f60b, 5.15.212; azl3 kernel 6.6.144.1-1 on Azure Linux 3.0 6.6.145.2-1.

Low priority for now. Upgrade to Linux Linux 1b41cbe05b184f8861712f0806cc0c4f5d8c6dfe, 3f1f755366687d051174739fb99f7d560202f60b, 5.15.212; azl3 kernel 6.6.144.1-1 on Azure Linux 3.0 6.6.145.2-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 7.8 · v3.1—Proof of concept Fix available
Published
Jul 27, 2026
Updated
Nov 3, 2026
EPSS
0.3% · 32th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 6b099d285d7ed324494b6d684f377aa103856118, 6.14affected
    • 057dbc5b72e9fcac439cd561c3a539b8a0edeb92 and later · before ab855641241387db062a5e41d9ad6b8561542572affected · git
    • 2532adbfe917c0e71dba2650ffc6efe396314c87 and later · before c66bd2626c2764f23764ff0f8277f44a9cfe8349affected · git
    • 4b1a0ee6164c7204c68ab5a9c48c07bfe8852485 and later · before d573250d228401f707f4dbc09d11227a6215ee5faffected · git
    • e6610f9c08b4c04cf7949c10fc246c071d00e935 and later · before f1efff8858403191361a01269c6fe8dd7f55a385affected · git
    • a1e64addf3ff9257b45b78bc7d743781c3f41340 and later · before dbd14f736be02cfe73049bd801af89becd1a0749affected · git
    • a1e64addf3ff9257b45b78bc7d743781c3f41340 and later · before 1b41cbe05b184f8861712f0806cc0c4f5d8c6dfeaffected · git
    • a1e64addf3ff9257b45b78bc7d743781c3f41340 and later · before 3f1f755366687d051174739fb99f7d560202f60baffected · git
    • 5.15.180 and later · before 5.15.212affected · semver
    • 6.1.132 and later · before 6.1.178affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:10kernelbefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-64kbefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-64k-corebefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-64k-debugbefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-64k-debug-corebefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-64k-debug-develbefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-64k-debug-devel-matchedbefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-64k-debug-modulesbefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-corebefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-extrabefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-64k-develbefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-64k-devel-matchedbefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-64k-modulesbefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-64k-modules-corebefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-64k-modules-extrabefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-corebefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-cross-headersbefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-debugbefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-debug-corebefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-debug-develbefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-debug-devel-matchedbefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-debug-modulesbefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2
AlmaLinux:10kernel-debug-modules-corebefore 6.12.0-211.46.1.el10_26.12.0-211.46.1.el10_2

+96

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2024-14040Jul 26, 2026 · net: nexthop: Increase weight to u16
    31Monitor
  • ← EarlierCVE-2026-64530Jul 26, 2026 · net/sched: cls_api: Handle TC_ACT_CONSUMED in tcf_qevent_handle
    39Monitor
  • Later →CVE-2026-64532Jul 27, 2026 · fs/ntfs3: bound NTFS_DE view.data_off in UpdateRecordData{Root,Allocation}
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux1b41cbe05b184f8861712f0806cc0c4f5d8c6dfeVendor (CNA)
Linux Linux3f1f755366687d051174739fb99f7d560202f60bVendor (CNA)
Linux Linux5.15.212Vendor (CNA)
Linux Linux6.1.178Vendor (CNA)
Linux Linux6.12.97Vendor (CNA)
Linux Linux6.14Vendor (CNA)
Linux Linux6.6.145Vendor (CNA)
Linux Linuxab855641241387db062a5e41d9ad6b8561542572Vendor (CNA)
Linux Linuxc66bd2626c2764f23764ff0f8277f44a9cfe8349Vendor (CNA)
Linux Linuxd573250d228401f707f4dbc09d11227a6215ee5fVendor (CNA)
Linux Linuxdbd14f736be02cfe73049bd801af89becd1a0749Vendor (CNA)
Linux Linuxf1efff8858403191361a01269c6fe8dd7f55a385Vendor (CNA)
azl3 kernel 6.6.144.1-1 on Azure Linux 3.06.6.145.2-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
almalinux:kernel5.14.0-687.38.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k5.14.0-687.38.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-core5.14.0-687.38.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug5.14.0-687.38.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-core5.14.0-687.38.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel5.14.0-687.38.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched5.14.0-687.38.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules5.14.0-687.38.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-core5.14.0-687.38.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra5.14.0-687.38.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel5.14.0-687.38.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel-matched5.14.0-687.38.1.el9_8 · AlmaLinux:9Package registry (OSV)
debian:linux6.1.180-1 · Debian:12Package registry (OSV)
debian:linux-6.126.12.100-1~deb12u1 · Debian:12Package registry (OSV)
red hat:bpftool-debuginfo0:7.0.0-284.186.1.el9_2 · Red Hat:rhel_e4s:9.2::appstreamPackage registry (OSV)
red hat:kernel-64k-debug-debuginfo0:5.14.0-284.186.1.el9_2 · Red Hat:rhel_e4s:9.2::appstreamPackage registry (OSV)
red hat:kernel-64k-debug-devel0:5.14.0-284.186.1.el9_2 · Red Hat:rhel_e4s:9.2::appstreamPackage registry (OSV)

+10

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×4

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:02026-07-29
Proof-of-concept repository on GitHubstars:32026-07-31
Proof-of-concept repository on GitHubstars:22026-08-01
Proof-of-concept repository on GitHubstars:112026-08-03

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. First PoC+2 d
  3. TodayNov 9, 2026+105 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-639848 days apartipv6: rpl: fix hdrlen overflow in ipv6_rpl_srh_decompress()
    39Monitor
  • CVE-2026-6815814 days apartlibceph: Fix multiplication overflow in decode_new_up_state_weight()
    39Monitor
  • CVE-2026-7201419 days apartdrbd: reject data replies with an out-of-range payload size
    39Monitor
  • CVE-2025-68794195 days apartiomap: adjust read range correctly for non-block-aligned positions
    39Monitor
  • CVE-2026-645222 days apartnet/mlx5e: Fix eswitch mode block underflow on IPsec acquire SA
    35Monitor
  • CVE-2026-6459810 days apartsmb/client: Fix error code in smb2_aead_req_alloc()
    35Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-190 · Integer Overflow or Wraparound

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (11 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records