CVE-2026-56444
CVE-2026-56444: 1 tracked advisory record across Red Hat. Compare source-reported impact, fixes and remediation.
Compare the source-linked records below. Ratings and product/version details belong to each advisory; they are not a single CVE-wide score or proof that every listed product is affected. How VulniPulse collects and checks evidence.
Vendor advisory comparison
Red Hat
1 advisory- Advisory severityLow3.7
Low [CVE-2026-56444] Denial of Service due to incorrect client reply accounting with specific serve-expired configuration
CVE-2026-56444Source published Source updated
In NLnet Labs Unbound 1.20.0 up to and including 1.25.1, when Unbound is configured with 'serve-expired: yes' and 'serve-expired-client-timeout > discard-timeout > 0' (contrary to the suggested values), the discard-timeout branch during the serve expired logic drops an aged client reply without performing the correct accounting for the number of reply addresses for the query. Other identical branches outside of serve expired perform the correct decrement. Since the counter is never decremented in such scenario, it can reach the maximum limit and new clients for duplicate in-flight queries are silently dropped resulting in degradation of resolution service. A malicious actor can exploit the vulnerability by querying the resolver for a client-controlled slow-on-demand authoritative zone…
- Affected products in this advisory
- Red Hat Hardened Images
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4
1 more entries in the full advisory.
- Source-reported affected versions
- 1.20.0
- 1.25.1
- Source-reported fixed versions
- unbound-main-1.25.2-0.1.hum1
- RHSA-2026:43588
- Mitigation guidance
- To mitigate this issue, ensure that Unbound is configured with `serve-expired-client-timeout` not greater than `discard-timeout` when `serve-expired: yes` is enabled. Alternatively, disable the `serve-expired` feature if it is not required. Red Hat's default configurations for Unbound prevent this vulnerability from being exploited.
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