3.7

CVE-2026-35501: nlnet labs unbound

CVSS: 3.7v3.1LowReceived
Published 21-10-2026Last modified 21-10-2026
Open JSON

Vulnerability summary

CVE-2026-35501 is a low (CVSS 3.7) vulnerability in nlnet labs unbound. EPSS estimates a 0.11% chance of exploitation in the next 30 days, higher than 1.1% of scored vulnerabilities.

Overall risk
15/100
0100
Low · default modelHow is this calculated?
CVSS score
3.7/10
010
Low · v3.1 (CVE.org)
EPSS score
0.11%
0%100%
Low · Change unavailable
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 21-10-2026
    PublishedVulnerability first disclosed.

Description

When NLnet Labs Unbound 1.0.1 up to and including version 1.26.1 is configured with both a root trust anchor and an additional 'trust-anchor:' for an island-of-security zone whose parent is provably insecure under the root chain, a malicious actor with a forged NSEC reply with the SOA bit cleared can trick Unbound to treat the configured trust island as insecure. This happens because the DNSSEC validator in Unbound accepts and caches the NSEC insecure response bypassing the RRSIG validation that the validator was supposed to do. The acceptance of the NSEC record at the trust anchor apex was allowed due to and old fix for type DS and NSEC queries from clients when trust anchor for that name existed.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.11%

Chance of exploitation in the next 30 days

Percentile

1%

Versus all other CVEs

30-day change

Change unavailable

Change unavailable

21-10-202621-10-2026
EPSS score
0.11%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Nlnet labs1 product

1 vendor · 1 product

References

1 links