CVE-2026-56444

MEDIUMPre-NVD 5.95.9
EchelonGraph scoreLOW confidence

This medium-severity CVE scores 5.9 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: secondary
5.9
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: —CVSS: 5.9Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
5.9
EG Score
5.9(low)
EPSS
—
KEV
Not listed

Published

July 22, 2026

Last Modified

July 22, 2026

Advisory Details (1)

Auto-updated Jul 22, 2026
No patch confirmed yet.
generic
https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-56444.txt

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 3× in last 7d / 3× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-22 14:54 UTCEG score recompute
  2. 2026-07-22 13:17 UTCEG score recompute
  3. 2026-07-22 13:17 UTCMITRE cvelistV5first tracked

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Frequently asked(4)

What is CVE-2026-56444?
CVE-2026-56444 is a medium vulnerability published on July 22, 2026. 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…
When was CVE-2026-56444 disclosed?
CVE-2026-56444 was first published in the National Vulnerability Database on July 22, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
What is the CVSS score of CVE-2026-56444?
CVE-2026-56444 has a CVSS v3 base score of 5.9 (NVD). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2026-56444?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-56444, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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