Red Hat Security Advisory: unbound security update
A heap overflow vulnerability exists in Unbound DNS resolver when processing multiple NSID, cookie, and padding EDNS options. This flaw can cause the Unbound service to crash, resulting in denial of service (DoS). The vulnerability affects certain versions of Unbound as shipped by Red Hat. No mitigation is currently available that meets Red Hat's criteria for ease of use and stability.
AI Analysis
Technical Summary
The vulnerability (CVE-2026-42944) in Unbound arises from incorrect calculation of buffer size when encoding multiple Name Server Identifier (NSID), EDNS Cookie, or EDNS Padding options in DNS reply packets. A remote attacker can trigger a heap overflow by sending specially crafted DNS replies containing these options. Successful exploitation leads to a denial of service by crashing the Unbound DNS resolver. The issue is tracked under CWE-131 (Incorrect Calculation of Buffer Size) and has a CVSS v3 base score of 7.5 (high) as per Red Hat and other sources. Red Hat's advisory notes that no suitable mitigation is currently available.
Potential Impact
Exploitation of this vulnerability results in denial of service by crashing the Unbound DNS resolver, making the service unavailable. There is no confidentiality or integrity impact reported. The attack requires no privileges or user interaction and can be performed remotely over the network.
Mitigation Recommendations
Red Hat states that no mitigation is currently available that meets their criteria for ease of use, deployment, applicability, or stability. Users should monitor Red Hat advisories for future updates or patches addressing this issue.
Red Hat Security Advisory: unbound security update
Description
A heap overflow vulnerability exists in Unbound DNS resolver when processing multiple NSID, cookie, and padding EDNS options. This flaw can cause the Unbound service to crash, resulting in denial of service (DoS). The vulnerability affects certain versions of Unbound as shipped by Red Hat. No mitigation is currently available that meets Red Hat's criteria for ease of use and stability.
Affected software
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability (CVE-2026-42944) in Unbound arises from incorrect calculation of buffer size when encoding multiple Name Server Identifier (NSID), EDNS Cookie, or EDNS Padding options in DNS reply packets. A remote attacker can trigger a heap overflow by sending specially crafted DNS replies containing these options. Successful exploitation leads to a denial of service by crashing the Unbound DNS resolver. The issue is tracked under CWE-131 (Incorrect Calculation of Buffer Size) and has a CVSS v3 base score of 7.5 (high) as per Red Hat and other sources. Red Hat's advisory notes that no suitable mitigation is currently available.
Potential Impact
Exploitation of this vulnerability results in denial of service by crashing the Unbound DNS resolver, making the service unavailable. There is no confidentiality or integrity impact reported. The attack requires no privileges or user interaction and can be performed remotely over the network.
Mitigation Recommendations
Red Hat states that no mitigation is currently available that meets their criteria for ease of use, deployment, applicability, or stability. Users should monitor Red Hat advisories for future updates or patches addressing this issue.
Technical Details
- Gcve Source
- db.gcve.eu
- Csaf Category
- csaf_security_advisory
- Csaf Version
- 2.0
- Publisher
- Red Hat Product Security
- Advisory Id
- RHSA-2026:24365
- Cve Count
- 2
- Additional Cves
- ["CVE-2026-42959"]
- State
- PUBLISHED
Threat ID: 6a27320ee29bf47b509bf305
Added to database: 06/08/2026, 21:20:14 UTC
Last enriched: 09/12/2026, 22:47:06 UTC
Last updated: 09/14/2026, 22:01:34 UTC
Views: 997
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