NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to a degradation of service attack related to parsing long lists of incoming… (CVE-2026-41292)
NLnet Labs Unbound versions up to and including 1.25.0 are vulnerable to a denial of service condition caused by processing excessive EDNS options in DNS queries. Attackers can send queries with too many EDNS options, causing Unbound threads to be held up while parsing and building internal data structures, leading to degraded service or denial of service. Version 1.25.1 includes a fix that limits the number of acceptable incoming EDNS options to 100. Red Hat has released security advisories and updated packages addressing this vulnerability for their hardened images and Red Hat Enterprise Linux 10 distributions.
AI Analysis
Technical Summary
The vulnerability (CVE-2026-41292) affects NLnet Labs Unbound up to and including version 1.25.0. It allows an adversary to degrade or deny service by sending DNS queries with excessive EDNS options, which causes Unbound threads to be occupied parsing these options and creating internal data structures. This resource exhaustion can be leveraged in coordinated attacks to impact availability. The issue is addressed in Unbound version 1.25.1 by limiting the number of accepted EDNS options to 100. Red Hat has issued security advisories (RHSA-2026:24013 and RHSA-2026:36320) providing updated packages for Red Hat Hardened Images and Red Hat Enterprise Linux 10 that include this fix.
Potential Impact
An attacker can cause degradation or denial of service on systems running vulnerable Unbound versions by sending DNS queries with an excessive number of EDNS options. This results in Unbound threads being held hostage during parsing, reducing the resolver's ability to process legitimate queries and potentially causing service outages or degraded DNS resolution performance.
Mitigation Recommendations
A fix is available in Unbound version 1.25.1, which limits the number of acceptable incoming EDNS options to 100. Red Hat has released updated packages for Red Hat Hardened Images and Red Hat Enterprise Linux 10 that include this patch. Users should apply these updates promptly to remediate the vulnerability. Refer to Red Hat advisories RHSA-2026:24013 and RHSA-2026:36320 for detailed update instructions.
NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to a degradation of service attack related to parsing long lists of incoming… (CVE-2026-41292)
Description
NLnet Labs Unbound versions up to and including 1.25.0 are vulnerable to a denial of service condition caused by processing excessive EDNS options in DNS queries. Attackers can send queries with too many EDNS options, causing Unbound threads to be held up while parsing and building internal data structures, leading to degraded service or denial of service. Version 1.25.1 includes a fix that limits the number of acceptable incoming EDNS options to 100. Red Hat has released security advisories and updated packages addressing this vulnerability for their hardened images and Red Hat Enterprise Linux 10 distributions.
CVSS v4.0
Affected software
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability (CVE-2026-41292) affects NLnet Labs Unbound up to and including version 1.25.0. It allows an adversary to degrade or deny service by sending DNS queries with excessive EDNS options, which causes Unbound threads to be occupied parsing these options and creating internal data structures. This resource exhaustion can be leveraged in coordinated attacks to impact availability. The issue is addressed in Unbound version 1.25.1 by limiting the number of accepted EDNS options to 100. Red Hat has issued security advisories (RHSA-2026:24013 and RHSA-2026:36320) providing updated packages for Red Hat Hardened Images and Red Hat Enterprise Linux 10 that include this fix.
Potential Impact
An attacker can cause degradation or denial of service on systems running vulnerable Unbound versions by sending DNS queries with an excessive number of EDNS options. This results in Unbound threads being held hostage during parsing, reducing the resolver's ability to process legitimate queries and potentially causing service outages or degraded DNS resolution performance.
Mitigation Recommendations
A fix is available in Unbound version 1.25.1, which limits the number of acceptable incoming EDNS options to 100. Red Hat has released updated packages for Red Hat Hardened Images and Red Hat Enterprise Linux 10 that include this patch. Users should apply these updates promptly to remediate the vulnerability. Refer to Red Hat advisories RHSA-2026:24013 and RHSA-2026:36320 for detailed update instructions.
Technical Details
- Gcve Source
- db.gcve.eu
- Csaf Category
- csaf_security_advisory
- Csaf Version
- 2.0
- Publisher
- Red Hat Product Security
- Advisory Id
- RHSA-2026:24013
- Cve Count
- 3
- Additional Cves
- ["CVE-2026-42534","CVE-2026-44390"]
- Cvss Version
- null
Threat ID: 6a5c47772a4a8d5989eb4fb5
Added to database: 07/19/2026, 03:41:43 UTC
Last enriched: 07/30/2026, 15:22:01 UTC
Last updated: 07/31/2026, 19:22:58 UTC
Views: 32
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.