CVE-2026-77860: NLnet Labs Unbound · Multiple Operations on Resource in Single-Operation Context
Affects NLnet Labs UnboundSource CVE Database V5
Mentioned vulnerabilities
Not known to be exploited · CVSS 3.7 Low : upgrade to 1.26.1 when convenient.
Data as of 31 Oct 2026, 08:20 UTC
- EPSS
- 0.3% chance of exploitation in 30 days – higher than 22% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 1.26.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:LExploitation evidence
Disclosed: evidence found.
CVE published 16 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Upgrade NLnet Labs Unbound to 1.26.1.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| NLnet LabsUnbound | Affected
| Fixed in
|
AI-suggested
No explicit patch or fix is stated in the provided data. Since this vulnerability is related to a specific code path and countermeasure bypass, generic mitigations unrelated to this context are not recommended.
Description
NLnet Labs Unbound versions 1.20.0 through 1.26.0 contain a vulnerability in the 'serve-expired' code path that allows a double decrement of the 'wait-limit' counter per client IP. This flaw can be exploited by an attacker controlling an authoritative zone with short TTLs to bypass a DNS query rate-limiting countermeasure introduced for DNSBomb (CVE-2024-33655). The attacker can maintain the per-client counter at or below the configured limit indefinitely, allowing an arbitrary number of pending queries from a single source IP. The vulnerability has a CVSS score of 3.7 and is classified as medium severity.