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
Severity and exploitation
KEV coverage does not rule out exploitation.
Assessment vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:LSeverity
high7.3CVSS measures technical severity, not the likelihood of an attack.
Known exploitation
Not listed in the checked CISA KEV catalog
Absence from CISA KEV does not rule out attacks.
Public exploit
Not established by this record
Missing evidence does not mean no public exploit exists.
Remediation
Source guidance available
Review the recorded instructions. Guidance may be a workaround rather than a fixed version.
What this means
Robots::Validate versions 0.4.3 before 0.4.10 for Perl may incorrectly report clients as imposter robots due to carried-over User-Agent matcher state. A remote client can exploit this to block other visitors. The weakness is exposure of data element to wrong session.
Summarized by @cf/meta/llama-3.3-70b-instruct-fp8-fast. Verify details against the original sources.Attack conditions
No attack-condition excerpt has been identified here. Review the full source description and references for authentication, network access, and configuration requirements.
Review supporting sources →Affected versions
Check the exact model, release, and any platform requirements against your installation.
Vendor not supplied · CPANSec
Robots-Validate
1 range
Vendor not supplied · CPANSec
Robots-Validate
Package identity
pkg:cpan/Robots-ValidateIdentity supplied by CPANSec. Version matching requires compatible range evidence.
Compare with this publisher’s ranges. This does not inspect your installation.
affected
0.4.3 → before 0.4.10
custom versions
Other versions: unaffected
What to do
Compare your installed product and version with the affected versions above. A matching product name alone does not confirm exposure.
Upgrade to Robots-Validate v0.4.10 or later.
Deployments with Algorithm::AhoCorasick::XS should upgrade to v0.4.11, which fixed a bug with using that version.
cve.new guidance unless attributed to a publisher. This page does not inspect your installation.
Public exploit evidence
No public exploit reference is identified in the imported evidence. This is not a claim that no exploit exists.
Original source description
Read the full publisher 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.
References
4 sourcesInside the record
Evidence available
Describes the evidence in this view, not whether the product is safe.
Original records
CVE-2026-112921View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.
cve.new JSON →Underlying weaknesses
The source’s classification of what caused the vulnerability.
Contributing organizations · 3
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Additional data publisher
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Timeline
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Source updated
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Last imported by cve.new
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What changed
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