Metrics
Affected Vendors & Products
No advisories yet.
Solution
This issue is fixed starting with version 1.26.1
Workaround
No workaround given by the vendor.
Wed, 16 Sep 2026 15:30:00 +0000
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ssvc
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Wed, 16 Sep 2026 12:15:00 +0000
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| Weaknesses | CWE-911 | |
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threat_severity
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threat_severity
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Wed, 16 Sep 2026 08:45:00 +0000
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| Description | In NLnetLabs Unbound 1.20.0 up to and including 1.26.0, a vulnerability on the 'serve-expired' code path can cause a double decrement on the 'wait-limit' counter per client IP essentially bypassing one of the counter measures that was introduced for DNSBomb (CVE-2024-33655). A malicious actor can exploit this by controlling an authoritative zone with short TTL, so cached entries expire quickly. Each 'slow' query, one the attacker's authoritative never answers, is followed by one query for an expired cached name, which is answered immediately via the 'serve-expired' path and decrements the counter twice. This second query was named 'pump'. By alternating slow queries and pumps, the attacker keeps the per-client counter at or below the configured 'wait-limit' indefinitely, and can hold an arbitrary number of pending queries from a single source IP, up to the global mesh quota (num-queries-per-thread); eventually bypassing one of the counter measures introduced for DNSBomb (CVE-2024-33655). This vulnerability is present on the 'serve-expired' code path. | |
| Title | 'serve-expired' can bypass Unbound 'wait-limit' | |
| Weaknesses | CWE-675 | |
| References |
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| Metrics |
cvssV3_1
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Projects
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Status: PUBLISHED
Assigner: NLnet Labs
Published:
Updated: 2026-09-16T14:45:35.788Z
Reserved: 2026-09-07T14:06:21.971Z
Link: CVE-2026-77860
Updated: 2026-09-16T14:45:31.286Z
Status : Received
Published: 2026-09-16T09:17:05.623
Modified: 2026-09-16T15:17:50.837
Link: CVE-2026-77860
OpenCVE Enrichment
Updated: 2026-09-16T15:00:07Z