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CVE-2026-97206

DNS-over-QUIC (DoQ) path-migration can lead to use-after-free on multi-threaded deployments.

Products / packages NLnet Labs Unbound

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Severity and exploitation

Not in CISA KEV

KEV coverage does not rule out exploitation.

KEV checked 14/11/2026, 21:15:32 UTC
NLnet Labs · CVSS:3.1 · 7.5
Assessment vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Severity

high7.5

CVSS measures technical severity, not the likelihood of an attack.

Known exploitation

Not listed in the checked CISA KEV catalog

Absence from CISA KEV does not rule out attacks.

Public exploit

Not established by this record

Missing evidence does not mean no public exploit exists.

Remediation

Source guidance available

Review the recorded instructions. Guidance may be a workaround rather than a fixed version.

What this means

NLnet Labs Unbound versions 1.22.0 to 1.26.1 have a use-after-free weakness, triggered by a remote DNS-over-QUIC client under multi-threaded operation, potentially leading to a crash. A client-triggered QUIC path migration can cause a stale pointer dereference. The issue is related to DNS-over-QUIC lifetime bugs.

Summarized by @cf/meta/llama-3.3-70b-instruct-fp8-fast. Verify details against the original sources.

Attack conditions

No attack-condition excerpt has been identified here. Review the full source description and references for authentication, network access, and configuration requirements.

Review supporting sources →

Affected versions

Check the exact model, release, and any platform requirements against your installation.

NLnet Labs · NLnet Labs

Unbound

1 range
NLnet Labs version evidence

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affected

1.22.0 → before 1.26.2

semver versions

unaffected

unknown

Other versions: unaffected

Automatic dependency matching is unavailable for this record. Use the product evidence and publisher’s instructions to check your installation.

What to do

Compare your installed product and version with the affected versions above. A matching product name alone does not confirm exposure.

This issue is fixed starting with version 1.26.2

NLnet Labs guidance ↗

cve.new guidance unless attributed to a publisher. This page does not inspect your installation.

Public exploit evidence

No public exploit reference is identified in the imported evidence. This is not a claim that no exploit exists.

Original source description

Read the full publisher 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.

References

1 sources
www.nlnetlabs.nl/downloads/unbound/CVE-2026-97206.txt
Vendor advisoryNLnet Labs

Inside the record

Evidence available

Package identity · not supplied
Version evidence
Remediation guidance
Weakness classification
Additional publishers

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2026-97206

View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.

cve.new JSON →

Underlying weaknesses

The source’s classification of what caused the vulnerability.

CWE-416 ↗

CWE-416: Use After Free

NLnet Labs

Related →
Contributing organizations · 2
NLnet Labs

Assigning organization

2026-10-21
CISA-ADP

Additional data publisher

2026-10-29

Timeline

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  1. Advisory published

    Publication date supplied by the source.

  2. Source updated

    Latest modification date supplied by the source.

  3. Last imported by cve.new

    Latest catalog import, not the date we first saw this advisory.

What changed

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