CVE-2026-112921: CWE-488 Exposure of Data Element to Wrong Session
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.
Affected software
pkg:github/Robots-ValidateRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- CPANSec
- Date Reserved
- 2026-10-19T21:17:46.149Z
- State
- PUBLISHED
Threat ID: 6ad936224d27ba8daa06ea5c
Added to database: 10/21/2026, 22:01:06 UTC
Last updated: 10/21/2026, 22:01:06 UTC
Views: 1
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