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CVE-2026-82717

Nlnetlabs Unbound remote code execution

9.8 CRITICALEPSS 0.78%
  1. Published16 Sept 2026

Description

In NLnet Labs Unbound up to and including 1.26.0, a vulnerability was found in that can progressively corrupt heap memory and under certain systems and compilation options could lead to remote code execution. The vulnerability starts when CNAME synthesis during an upstream response needs to enforce(rewrite) a max TTL value in the packet buffer. Coupled with a compression pointer that points to the overwritten value and invalidates the domain name, it leads to an error path that does not properly move the buffer position and allows for the heap buffer overflow. Since this is heavily reliant on heap memory layout, results are memory corruption that eventually leads to a crash and under specific systems and compilation options remote code execution.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Nlnetlabs Unbound< 1.26.1

Remediation

Fixed in
Nlnetlabs Unbound≥ 1.26.1

References

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Frequently asked

Is CVE-2026-82717 being actively exploited?

CVE-2026-82717 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.78%.

How severe is CVE-2026-82717?

CVE-2026-82717 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 0.78% probability of exploitation.

Which products are affected by CVE-2026-82717?

Affected products include Nlnetlabs Unbound.

How do I fix CVE-2026-82717?

Upgrade affected software to a fixed version, for example Nlnetlabs Unbound 1.26.1 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-82717 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.