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Vulnerabilities

Vulnerability · CVE-2026-4891

A heap-based out-of-bounds read vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a crafted DNS packet.

Published May 11, 2026 · catalog updated Aug 25, 2026 · A heap-based out-of-bounds read

Check if you run it

No confirmed exploitation is on record for CVE-2026-4891. EPSS is 0.84%. Act only if a listed version of A heap-based out-of-bounds read is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (A heap-based out-of-bounds read).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium5.3
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.84%
Remediation
Not established
Affected products
See sources for product scope

A heap-based out-of-bounds read vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a crafted DNS packet.

No affected version ranges are stored yet. Use the vendor advisory before you decide this record does not apply.

How to fix CVE-2026-4891

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-4891. EPSS is 0.84%. Act only if a listed version of A heap-based out-of-bounds read is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-125: Out-of-bounds Read. EPSS 0.84%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. May 11, 2026 · NIST NVD

    Detected

    A heap-based out-of-bounds read vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a crafted DNS packet.

  2. Aug 25, 2026 · NIST NVD

    Updated

    A heap-based out-of-bounds read vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a crafted DNS packet.

Sources

  • CVE.orgVulnerability recordCVE-2026-4891

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-4891

    30-day exploitation probability 0.8%

    first.org
  • NIST NVDVulnerability recordCVE-2026-4891

    A heap-based out-of-bounds read vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a crafted DNS packet.

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.