CVE-2026-97206
DNS-over-QUIC (DoQ) path-migration can lead to use-after-free on multi-threaded deployments.
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
DNS-over-QUIC (DoQ) path-migration can lead to use-after-free on multi-threaded deployments.
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.
- Record
CVE-2026-97206- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-416
- Updated
- 2026-11-02
EUVDEUVD-2026-107154
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.
- Record
EUVD-2026-107154- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-jc7q-6h55-rr57
NLnet Labs Unbound, 1.22.0 up to and including version 1.26.1, contains a DNS-over-QUIC (DoQ)...
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.
- Record
GHSA-jc7q-6h55-rr57- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-416
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2026-97206- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-416
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2026-97206
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.
- Record
DEBIAN-CVE-2026-97206- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-97206
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.
- Record
UBUNTU-CVE-2026-97206- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVAZL-109824 No score
CVE-2026-97206 affecting package unbound for versions less than 1.26.2-1
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.
- Record
AZL-109824- Updated
- 2026-11-06
OSVMGASA-2026-0571 No score
Updated unbound package fixes security vulnerabilities
Bypass of a configured island trust anchor underneath an insecure parent from an attacker-controlled NSEC record. Possible insecure NXDOMAIN for non-existing records under a configured island trust anchor underneath an insecure parent. Aggregate DNS name chained pointer decompression work leads to degradation of service. DNS-over-QUIC path-migration can lead to use-after-free on multi-threaded deployments. Possible cache poisoning vulnerability via a cache side-channel exposed by 'unwanted-reply-threshold'.
- Record
MGASA-2026-0571- Updated
- 2026-11-02
OSVopenSUSE-SU-2026:12257-1 No score
libunbound8-1.26.2-1.1 on GA media
These are all security issues fixed in the libunbound8-1.26.2-1.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2026:12257-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
unboundAzure Linux:3 |
before 1.26.2-1 | 1.26.2-1 |
unboundDebian:12 |
All versions, plus listed versions 1.17.1-21.17.1-2+deb12u11.17.1-2+deb12u21.17.1-2+deb12u31.17.1-2+deb12u4 Show 22 moreShow less1.17.1-2+loong641.18.0-11.18.0-21.19.1-11.19.2-11.20.0-11.21.1-11.22.0-11.22.0-21.23.1-11.24.0-11.24.0-21.24.1-11.24.1-21.24.2-11.25.0-11.25.1-11.25.2-11.26.0-11.26.0-21.26.1-11.26.2-1 |
None known |
unboundDebian:13 |
before 1.26.2-0+deb13u1, plus listed versions 1.22.0-21.22.0-2+deb13u11.22.0-2+deb13u21.22.0-2+deb13u31.23.1-1 Show 12 moreShow less1.24.0-11.24.0-21.24.1-11.24.1-21.24.2-11.25.0-11.25.1-11.25.2-11.26.0-11.26.0-21.26.1-0+deb13u11.26.1-1 |
1.26.2-0+deb13u1 |
unboundDebian:14 |
before 1.26.2-1, plus listed versions 1.22.0-21.23.1-11.24.0-11.24.0-21.24.1-1 Show 8 moreShow less1.24.1-21.24.2-11.25.0-11.25.1-11.25.2-11.26.0-11.26.0-21.26.1-1 |
1.26.2-1 |
unboundMageia:10 From an advisory covering 5 CVEs |
before 1.26.2-1.mga10 | 1.26.2-1.mga10 |
unboundUbuntu:Pro:14.04:LTS |
All versions, plus listed versions 1.4.20-11.4.21-11.4.21-1ubuntu11.4.21-1ubuntu21.4.22-1ubuntu1 Show 11 moreShow less1.4.22-1ubuntu21.4.22-1ubuntu31.4.22-1ubuntu41.4.22-1ubuntu4.14.04.11.4.22-1ubuntu4.14.04.21.4.22-1ubuntu4.14.04.31.4.22-1ubuntu4.14.04.3+esm11.4.22-1ubuntu4.14.04.3+esm21.4.22-1ubuntu4.14.04.3+esm31.4.22-1ubuntu4.14.04.3+esm41.4.22-1ubuntu4.14.04.3+esm5 |
None known |
unboundUbuntu:Pro:16.04:LTS |
All versions, plus listed versions 1.4.22-1ubuntu61.5.7-1ubuntu11.5.7-1ubuntu21.5.8-1ubuntu11.5.8-1ubuntu1.1 Show 5 moreShow less1.5.8-1ubuntu1.1+esm11.5.8-1ubuntu1.1+esm21.5.8-1ubuntu1.1+esm31.5.8-1ubuntu1.1+esm41.5.8-1ubuntu1.1+esm5 |
None known |
unboundUbuntu:Pro:18.04:LTS |
All versions, plus listed versions 1.6.5-11.6.7-11.6.7-1build11.6.7-1ubuntu11.6.7-1ubuntu2 Show 11 moreShow less1.6.7-1ubuntu2.11.6.7-1ubuntu2.21.6.7-1ubuntu2.31.6.7-1ubuntu2.41.6.7-1ubuntu2.51.6.7-1ubuntu2.61.6.7-1ubuntu2.6+esm21.6.7-1ubuntu2.6+esm31.6.7-1ubuntu2.6+esm41.6.7-1ubuntu2.6+esm51.6.7-1ubuntu2.6+esm6 |
None known |
unboundUbuntu:Pro:20.04:LTS |
All versions, plus listed versions 1.9.0-2ubuntu11.9.0-2ubuntu21.9.4-21.9.4-2ubuntu11.9.4-2ubuntu1.1 Show 11 moreShow less1.9.4-2ubuntu1.21.9.4-2ubuntu1.31.9.4-2ubuntu1.41.9.4-2ubuntu1.51.9.4-2ubuntu1.61.9.4-2ubuntu1.81.9.4-2ubuntu1.91.9.4-2ubuntu1.111.9.4-2ubuntu1.11+esm11.9.4-2ubuntu1.11+esm21.9.4-2ubuntu1.11+esm3 |
None known |
unboundUbuntu:22.04:LTS |
All versions, plus listed versions 1.13.1-1ubuntu11.13.1-1ubuntu31.13.1-1ubuntu51.13.1-1ubuntu5.11.13.1-1ubuntu5.2 Show 13 moreShow less1.13.1-1ubuntu5.31.13.1-1ubuntu5.41.13.1-1ubuntu5.51.13.1-1ubuntu5.71.13.1-1ubuntu5.81.13.1-1ubuntu5.101.13.1-1ubuntu5.111.13.1-1ubuntu5.121.13.1-1ubuntu5.131.13.1-1ubuntu5.141.13.1-1ubuntu5.151.13.1-1ubuntu5.161.13.1-1ubuntu5.17 |
None known |
Show 4 moreShow less
| Package | Affected | Fixed |
|---|---|---|
unboundUbuntu:24.04:LTS |
All versions, plus listed versions 1.17.1-21.18.0-2ubuntu11.18.0-2ubuntu21.19.1-1ubuntu11.19.2-1ubuntu1 Show 12 moreShow less1.19.2-1ubuntu31.19.2-1ubuntu3.11.19.2-1ubuntu3.21.19.2-1ubuntu3.31.19.2-1ubuntu3.41.19.2-1ubuntu3.51.19.2-1ubuntu3.61.19.2-1ubuntu3.71.19.2-1ubuntu3.81.19.2-1ubuntu3.91.19.2-1ubuntu3.101.19.2-1ubuntu3.12 |
None known |
unboundUbuntu:26.10 |
All versions, plus listed versions 1.24.2-1ubuntu21.25.1-1ubuntu11.25.1-1ubuntu3 |
None known |
unboundUbuntu:26.04:LTS |
All versions, plus listed versions 1.22.0-2ubuntu21.22.0-2ubuntu41.24.2-1ubuntu11.24.2-1ubuntu21.24.2-1ubuntu2.11.24.2-1ubuntu2.21.24.2-1ubuntu2.31.24.2-1ubuntu2.4 |
None known |
unboundopenSUSE:Tumbleweed From an advisory covering 5 CVEs |
before 1.26.2-1.1 | 1.26.2-1.1 |
Public exploits
Links only. Every CVE stores no exploit code.
| Source | Link | Date |
|---|---|---|
| PoC in GitHub | suominen/CVE-2026-97206 | 2026-10-22 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected | OSV | |
| affected | ||
| facts | OSV | |
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV, PoC in GitHub |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-97206 is a high vulnerability (CVSS 7.5) in Nlnet Labs Unbound, published October 21, 2026. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 0.33%, the 26th percentile. Fixed in unbound 1.26.2-1.
References
nlnetlabs.nl/downloads/unbound/CVE-2026-97206.txt
nvd.nist.gov/vuln/detail/CVE-2026-97206
github.com/advisories/GHSA-jc7q-6h55-rr57
security-tracker.debian.org/tracker/CVE-2026-97206
advisories.mageia.org/MGASA-2026-0571.html
bugs.mageia.org/show_bug.cgi?id=36568
Show 9 moreShow less
nlnetlabs.nl/projects/unbound/security-advisories
ubuntu.com/security/CVE-2026-97206
cve.org/CVERecord?id=CVE-2026-97206
community.nlnetlabs.nl/t/unbound-1-26-2-released/3495
suse.com/security/cve/CVE-2026-109125