VulnerabilityPublished 4 Nov 2026Updated 12 Nov 2026

CVE-2026-120640: Libcgi pm perl · CGI versions before 5.00 for Perl allow the POSTDATA, PUTDATA, PATCHDATA and

Affects libcgi-pm-perlSource GCVE Database

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Authoritative record:CVE-2026-120640· Medium 6.5

Not known to be exploited · CVSS 6.5 Medium.

Data as of 12 Nov 2026, 22:19 UTC

CVSS 3.1 base score

6.5Medium

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CISA-ADP	CVSS 3.1	6.5

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

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 12 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

Affected software

Product	Affected	Fixed in
Ubuntu 26.10libcgi-pm-perl`pkg:deb/ubuntu/libcgi-pm-perl?arch=source&distro=stonking`Other threats	Affected =4.71-1build1 =4.72-1	Fixed in–
Ubuntu 26.04 LTSlibcgi-pm-perl`pkg:deb/ubuntu/libcgi-pm-perl?arch=source&distro=resolute`Other threats	Affected =4.68-1 =4.71-1 =4.71-1build1	Fixed in–
Ubuntu 24.04 LTSlibcgi-pm-perl`pkg:deb/ubuntu/libcgi-pm-perl?arch=source&distro=noble`Other threats	Affected 4.57-1 – 4.63-1 5 affected builds	Fixed in–
Ubuntu 22.04 LTSlibcgi-pm-perl`pkg:deb/ubuntu/libcgi-pm-perl?arch=source&distro=jammy`Other threats	Affected =4.51-1 =4.53-1 =4.54-1	Fixed in–
Ubuntu 20.04 LTSlibcgi-pm-perl`pkg:deb/ubuntu/libcgi-pm-perl?arch=source&distro=focal`Other threats	Affected =4.44-1 =4.45-1 =4.46-1	Fixed in–
Ubuntu 18.04 LTSlibcgi-pm-perl`pkg:deb/ubuntu/libcgi-pm-perl?arch=source&distro=bionic`Other threats	Affected =4.36-1 =4.37-1 =4.38-1	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Until a fix is available, applications should avoid relying on param('POSTDATA') or similar parameters for security-sensitive JSON processing or implement additional validation to distinguish genuine request bodies from client-supplied parameters.

Description

CGI versions before 5.00 for Perl allow certain parameters (POSTDATA, PUTDATA, PATCHDATA, and XForms:Model) to be set from query strings or form fields, which can cause confusion between client-sent values and actual request bodies. This behavior enables a cross-site request forgery where an attacker can submit crafted POSTDATA to an endpoint that reads JSON from param('POSTDATA') without requiring CORS preflight.

Impact

An attacker can perform cross-site request forgery by submitting crafted parameters that the application mistakenly treats as legitimate request bodies. This can lead to unauthorized manipulation of JSON data processed by the application, potentially resulting in information disclosure or integrity violations. The CVSS score of 6.5 (medium severity) reflects the network attack vector, low complexity, no privileges required, no user interaction, and limited confidentiality and integrity impact.

Summary

The vulnerability in libcgi-pm-perl versions before 5.00 arises because the CGI module accepts POSTDATA, PUTDATA, PATCHDATA, and XForms:Model parameters from query strings or form fields in addition to storing non-form request bodies under these names. This ambiguity prevents applications from distinguishing between genuine request bodies and client-supplied parameters, allowing an attacker to forge requests that manipulate JSON parameters such as POSTDATA. This can be exploited via cross-site HTML forms to perform request forgery without CORS preflight checks.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 12 Nov 2026, 22:19 UTC

Technical details

References

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