Description
An information disclosure vulnerability in dnsmasq allows remote attackers to bypass source checks via a crafted DNS packet with RFC 7871 client subnet information.
Published: 2026-05-11
Score: 5.3 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

The vulnerability allows remote attackers to bypass source checks by sending a crafted DNS packet that includes RFC 7871 client subnet information. This flaw enables the disclosure of client subnet data that should otherwise be protected.

Affected Systems

dnsmasq is affected when it processes DNS queries containing RFC 7871 client subnet options. No specific product versions are listed, so all builds that support RFC 7871 and do not enforce source validation could be vulnerable.

Risk and Exploitability

The CVSS score is 5.3, indicating moderate severity. The EPSS score is 0.00049 (<1%), indicating a low exploitation probability, and the vulnerability is not listed in the CISA KEV catalog, so public exploitation data is limited. Attackers can exploit the flaw remotely by sending crafted DNS packets over the network that contain a client‑subnet option, without requiring local or authenticated access.

Generated by OpenCVE AI on May 13, 2026 at 04:23 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Upgrade dnsmasq to the latest version that addresses RFC 7871 client subnet handling.
  • Configure dnsmasq to ignore or drop client-subnet options during query processing if an immediate upgrade is not possible.
  • Implement firewall rules to block or rate-limit external DNS packets that contain a client-subnet option to reduce exposure.

Generated by OpenCVE AI on May 13, 2026 at 04:23 UTC.

Tracking

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Advisories
Source ID Title
Debian DSA Debian DSA DSA-6264-1 dnsmasq security update
History

Wed, 13 May 2026 03:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-200

Wed, 13 May 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-20
References
Metrics threat_severity

None

 threat_severity

Moderate

Tue, 12 May 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-200

Mon, 11 May 2026 21:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-200

Mon, 11 May 2026 20:45:00 +0000

Type Values Removed Values Added
References

Mon, 11 May 2026 19:30:00 +0000

Type Values Removed Values Added
References

Mon, 11 May 2026 19:15:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Mon, 11 May 2026 19:00:00 +0000

Type Values Removed Values Added
First Time appeared Dnsmasq
Dnsmasq dnsmasq
Weaknesses CWE-200
Vendors & Products Dnsmasq
Dnsmasq dnsmasq

Mon, 11 May 2026 18:45:00 +0000

Type Values Removed Values Added
References

Mon, 11 May 2026 17:30:00 +0000

Type Values Removed Values Added
Description An information disclosure vulnerability in dnsmasq allows remote attackers to bypass source checks via a crafted DNS packet with RFC 7871 client subnet information.
Title CVE-2026-4893
References

Subscriptions

Dnsmasq Dnsmasq
cve-icon MITRE

Status: PUBLISHED

Assigner: certcc

Published:

Updated: 2026-05-11T19:57:48.774Z

Reserved: 2026-03-26T13:12:03.722Z

Link: CVE-2026-4893

cve-icon Vulnrichment

Updated: 2026-05-11T18:28:48.460Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-05-11T18:16:41.593

Modified: 2026-05-12T14:15:46.747

Link: CVE-2026-4893

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-05-09T00:00:00Z

Links: CVE-2026-4893 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-05-13T04:30:05Z

Weaknesses