7.5

CVE-2026-97206: nlnet labs unbound Use After Free

CVSS: 7.5v3.1HighReceived
Published 21-10-2026Last modified 21-10-2026
Open JSON

Vulnerability summary

CVE-2026-97206 is a high (CVSS 7.5) Use After Free vulnerability in nlnet labs unbound. EPSS estimates a 0.26% chance of exploitation in the next 30 days, higher than 17% of scored vulnerabilities.

Overall risk
30/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
0.26%
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

NLnet Labs Unbound, 1.22.0 up to and including version 1.26.1, contains a DNS-over-QUIC (DoQ) lifetime bug reachable by a remote DoQ client under multi-threaded operation. A client-triggered QUIC path migration can enter stream/connection cleanup while a mesh reply still retains a pointer to the DoQ stream. Cleanup frees the DoQ stream and when the pending mesh reply later completes it dereferences a stale pointer leading to a crash.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.26%

Chance of exploitation in the next 30 days

Percentile

17%

Versus all other CVEs

30-day change

Change unavailable

Change unavailable

21-10-202621-10-2026
EPSS score
0.26%

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