VulnerabilityPublished 3 Nov 2026

CVE-2026-120640: CGI (Perl module) · Cross-Site Request Forgery

Affects CGI (Perl module)Source CVE Database V5

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Not known to be exploited : upgrade to 5.00 soon.

Data as of 4 Nov 2026, 01:00 UTC

Severity

High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

Thin evidence

One scorer or none

Patch: Available – fixed in 5.00

Exploitation evidence

Disclosed: evidence found.
CVE published 3 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 3 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade CGI (Perl module) to 5.00.

Affected software

Product	Affected	Fixed in
CGI	Affected <5.00	Fixed in 5.00
CPANCGI`pkg:cpan/CGI`Other threats	Affected <5.00	Fixed in 5.00

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AI-suggested

Upgrade to CGI version 5.00 or later, where this issue is fixed. No other mitigation guidance is provided, and no indication exists that the vulnerability is already mitigated or requires no action.

Description

CGI versions prior to 5.00 for Perl contain a cross-site request forgery (CSRF) vulnerability. The software allows certain parameters (POSTDATA, PUTDATA, PATCHDATA, and XForms:Model) to be set from query strings or form fields, which can be exploited by a malicious cross-site HTML form to send forged requests. This occurs because CGI cannot distinguish between client-sent values and the actual request body, enabling unauthorized actions without requiring CORS preflight checks.

Impact

An attacker can exploit this vulnerability to perform cross-site request forgery attacks without requiring CORS preflight, potentially causing unauthorized actions on behalf of authenticated users. This can lead to unauthorized data manipulation or administrative actions if the affected application relies on these parameters for critical operations.

Summary

The vulnerability in CGI versions before 5.00 arises from the ability to set POSTDATA, PUTDATA, PATCHDATA, and XForms:Model parameters via query strings or form fields, despite these parameters normally representing the request body. CGI stores non-form request bodies under these parameters but also accepts them from client-supplied inputs, making it impossible for applications to differentiate between genuine request bodies and forged parameters. This flaw enables cross-site request forgery attacks where a malicious HTML form can submit JSON data to an endpoint expecting JSON in param('POSTDATA'), bypassing normal cross-origin protections.

CWE-352Cross-Site Request Forgery (opens in a new tab)
Compound weaknessLikelihood of exploit: MediumCWE Top 25 (2025): #3OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Implementation
Ensure that the application is free of cross-site scripting issues (CWE-79), because most CSRF defenses can be bypassed using attacker-controlled script.
Architecture and Design
Generate a unique nonce for each form, place the nonce into the form, and verify the nonce upon receipt of the form. Be sure that the nonce is not predictable (CWE-330).
OWASP Cheat Sheets
REST Assessment (opens in a new tab)
REST Security (opens in a new tab)
Cross-Site Request Forgery Prevention (opens in a new tab)
Authorization Testing Automation (opens in a new tab)
Insecure Direct Object Reference Prevention (opens in a new tab)
OWASP ASVS 4.0.3
V13.2.3 (opens in a new tab)
V4.2.2 (opens in a new tab)
V13.3.2 (opens in a new tab)
Attack patterns
JSON Hijacking (aka JavaScript Hijacking) (opens in a new tab)
Cross-Domain Search Timing (opens in a new tab)
Cross Site Identification (opens in a new tab)
Cross Site Request Forgery (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 4 Nov 2026, 01:00 UTC

WeaknessesCWE-352

Technical details

References

Community reviews

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