CVE-2026-112921

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.

CVSS v3 7.3 HIGH

7.3^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact LOW

Scope UNCHANGED

References

Link	Resource
https://github.com/robrwo/Robots-Validate/commit/776a1456e6605492b7582ed25d3d5006ef384402.patch
https://metacpan.org/release/RRWO/Robots-Validate-v0.4.10/changes
https://metacpan.org/release/RRWO/Robots-Validate-v0.4.11/changes
http://www.openwall.com/lists/oss-security/2026/10/21/30

Configurations

No configuration.

History

30 Oct 2026, 18:17

Type	Values Removed	Values Added
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 7.3

22 Oct 2026, 01:16

Type	Values Removed	Values Added
References		() http://www.openwall.com/lists/oss-security/2026/10/21/30 -

21 Oct 2026, 22:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-21 22:16

Updated : 2026-10-30 18:17

NVD link : CVE-2026-112921

Mitre link : CVE-2026-112921

CVE.ORG link : CVE-2026-112921

JSON object : View

Products Affected

No product.

CWE

CWE-488

Exposure of Data Element to Wrong Session

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