Is CVE-2026-33278 actively exploited?

No active exploitation of CVE-2026-33278 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2026-33278 be exploited remotely?

Yes. CVE-2026-33278 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-33278?

CVE-2026-33278 has a CVSS score of 9.8 (CRITICAL).

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CRITICAL

CVE-2026-33278

CWE-416Published: May 20, 2026· Updated: May 20, 2026

9.8

CVSS v3.1

EPSS:0.24%probability of exploitation in 30 daysPercentile:47.7th

Official Description

NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator that enables denial of service and possible remote code execution as a result of deep copying a data structure and erroneously overwriting a destination pointer. An adversary can exploit the vulnerability by controlling a malicious signed zone and querying a vulnerable Unbound. When DS sub-queries need to suspend validation due to NSEC3 computational budget exhaustion (introduced in Unbound 1.19.1), Unbound deep-copies response messages to preserve them across memory region teardown. A struct-assignment bug overwrites the destination's pointer with the source's pointer. After the sub-query region is freed, the resumed validator dereferences this dangling pointer, triggering a crash or potentially enabling arbitrary code execution. Unbound 1.25.1 contains a patch with a fix to preserve the correct pointer when deep copying the data structure.

NVD Source

Technical Analysis

CVE-2026-33278 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

From a weakness classification perspective (CWE-416): Use-after-free vulnerabilities involve accessing memory after it has been freed, often enabling arbitrary code execution.