CVE-2026-45913

Local denial of service via unpaired counter decrement

Published May 27, 2026 · Updated May 27, 2026

Denial of service in the Linux Kernel bridge multicast component allows local users to trigger a kernel warning during MDB flushes. The code conditionally increments mdb_n_entries when enabling a port-VLAN context but later decrements it during entry deletion, allowing a flush to perform an unmatched decrement. Triggering requires privileges to create and reconfigure a VLAN-aware bridge; the demonstrated effect is a warning, which becomes a kernel panic when panic_on_warn is enabled.

CVSS severity5.5
Medium
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in the Linux Kernel bridge multicast component allows local users to trigger a kernel warning during MDB flushes. The code conditionally increments mdb_n_entries when enabling a port-VLAN context but later decrements it during entry deletion, allowing a flush to perform an unmatched decrement. Triggering requires privileges to create and reconfigure a VLAN-aware bridge; the demonstrated effect is a warning, which becomes a kernel panic when panic_on_warn is enabled.

The record

CVE
CVE-2026-45913
Published
May 27, 2026
Updated
May 27, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 27, 2026CVE publishedPublication date reported by the CVE source.
  2. May 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.3
  2. Affected versionversion=b57e8d870d522d905720052e6fd9c3bc9bc5f6fb <45525fdfd4cb612d7b414dd5cfa1f43892a7cd71
  3. Affected versionversion=b57e8d870d522d905720052e6fd9c3bc9bc5f6fb <724a405ce0309676f1e993c173382b4c4a022beb
  4. Affected versionversion=b57e8d870d522d905720052e6fd9c3bc9bc5f6fb <8b769e311a86bb9d15c5658ad283b86fc8f080a2
  5. Affected versionversion=b57e8d870d522d905720052e6fd9c3bc9bc5f6fb <d0fdad1bdd21a358cc2c85da3681ae27b86ce6ce
  6. Affected versionversion=b57e8d870d522d905720052e6fd9c3bc9bc5f6fb <fae260fc84e1eae8f590c7907e53e8768df2d986

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.3; version=b57e8d870d522d905720052e6fd9c3bc9bc5f6fb <45525fdfd4cb612d7b414dd5cfa1f43892a7cd71; version=b57e8d870d522d905720052e6fd9c3bc9bc5f6fb <724a405ce0309676f1e993c173382b4c4a022beb; version=b57e8d870d522d905720052e6fd9c3bc9bc5f6fb <8b769e311a86bb9d15c5658ad283b86fc8f080a2; version=b57e8d870d522d905720052e6fd9c3bc9bc5f6fb <d0fdad1bdd21a358cc2c85da3681ae27b86ce6ce; version=b57e8d870d522d905720052e6fd9c3bc9bc5f6fb <fae260fc84e1eae8f590c7907e53e8768df2d986

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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