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VulnerabilityPublished Updated

CVE-2026-41292: NLnet Labs Unbound · Inefficient Algorithmic Complexity

Affects NLnet Labs UnboundSource CVE Database V5

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Not known to be exploited · CVSS 6.6 Medium : upgrade to 1.25.1 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score
6.6Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.7% chance of exploitation in 30 days – higher than 54% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 1.25.1
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Red

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 20 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 1.25.1.

Affected software

ProductAffectedFixed in
NLnet LabsUnboundAffected
  • <1.25.1
Fixed in
  • 1.25.1

AI-suggested

A fix is available in Unbound version 1.25.1, which limits the number of acceptable incoming EDNS options to 100. Users should upgrade to version 1.25.1 or later to remediate this vulnerability. No other specific mitigations are indicated by the vendor advisory.

Description

NLnet Labs Unbound up to and including version 1.25.0 is vulnerable to a degradation of service attack related to parsing long lists of incoming EDNS options. An adversary sending queries with too many EDNS options can hold Unbound threads hostage while they are parsing and creating internal data structures for the options. Coordinated attacks can result in degradation and/or denial of service. Unbound 1.25.1 contains a patch with a fix to limit acceptable incoming EDNS options (100).

References

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