CVE-2026-56444
Is CVE-2026-56444 real, exploitable, or a false positive? Here's the community verdict.
signals
public sources
Moderate signals. Triage by your actual exposure and reachability.
baseline read
auto · not a community verdict
Low signal — verdict needed
Few public signals point to active risk. Whether a scanner hit here is a true or false positive depends on your version and config — community verdicts decide.
Based on CVSS
Confirm or dispute →CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
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 that can drive the counter past the threshold. Shipped defaults for 'serve-expired-client-timeout: 1800' and 'discard-timeout: 1900' make the branch unreachable.
References
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Related CVEs
Same weakness: CWE-772.
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