CVE-2026-112921
UNSCOREDDescription
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.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3.1 Vector
No CVSS vector data available.
Exploit Intelligence
Low risk: more likely to be exploited than 13% of all known CVEs.
References
Related Vulnerabilities
Other CWE-488 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2024-38367 | High | 8.2 | 11% | - | Fix |
| CVE-2024-6162 | High | 7.5 | 1.7% | - | Fix |
| CVE-2026-86492 | High | 8.5 | 0.9% | - | - |
| CVE-2026-80231 | Low | 3.7 | 0.9% | - | Fix |
| CVE-2025-1247 | High | 8.3 | 0.8% | - | - |
| CVE-2026-19931 | Medium | 6.5 | 0.7% | - | Fix |
Common questions
How do I fix CVE-2026-112921?
No published fix for CVE-2026-112921 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-112921 being actively exploited?
Not that we know of. CVE-2026-112921 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.23% is the estimated probability that it will be exploited in the next 30 days. That is higher than 13% of all scored CVEs.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-10-22.