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CVE-2026-112921

7.3 · HIGH

Robots::Validate versions from 0.4.3 before 0.4.10 for Perl report clients as imposter robots when User-Agent matcher state carries over from a previous request.

Published Oct 21, 2026CWE-488EPSS 0.36%

Overview

CVE-2026-112921 is a high-severity vulnerability. It was published on October 21, 2026 and has a CVSS 3.1 base score of 7.3 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.3, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

Robots::Validate versions from 0.4.3 before 0.4.10 for Perl report clients as imposter robots when User-Agent matcher state carries over from a previous request.

Each Robots::Validate object holds one pure-Perl Aho-Corasick search machine and feeds every User-Agent into it without resetting its state. A User-Agent that ends part-way through a robot name leaves the machine mid-match, so the next User-Agent checked by the same object can complete that name. That client's address is then checked against the robot's DNS rule, which it fails.

A remote client can use this to make a site that blocks bad robots block other visitors where the prefix User-Agent string is a suffix of a robot being validated.

Note that deployments with Algorithm::AhoCorasick::XS are also affected, since it was unused due to a different bug.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/robrwo/Robots-Validate/commit/776a1456e6605492b7582ed25d3d5006ef384402.patchRefmetacpan.org/release/RRWO/Robots-Validate-v0.4.10/changesRefmetacpan.org/release/RRWO/Robots-Validate-v0.4.11/changesRefwww.openwall.com/lists/oss-security/2026/10/21/30

How CyberStrike helps

Frequently asked questions

What is CVE-2026-112921?

CVE-2026-112921 is a high-severity vulnerability. It was published on October 21, 2026 and has a CVSS 3.1 base score of 7.3 (HIGH).

How severe is CVE-2026-112921?

This vulnerability has a CVSS 3.1 base score of 7.3, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-112921?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-112921?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-112921 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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