VDB-430917 · CVE-2026-120639 · GCVE-0-2026-120639

CPANSec CGI up to 4.x Header Processing lib/CGI.pm header/multipart_start/do_push injection

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
7.0	$0-$5k	1.00

Summaryinfo

A vulnerability marked as critical has been reported in CPANSec CGI up to 4.x. This vulnerability affects the function header/multipart_start/do_push of the file lib/CGI.pm of the component Header Processing. Performing a manipulation results in injection. This vulnerability is reported as CVE-2026-120639. The attack is possible to be carried out remotely. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in CPANSec CGI up to 4.x. It has been classified as critical. This affects the function header/multipart_start/do_push of the file lib/CGI.pm of the component Header Processing. The manipulation with an unknown input leads to a injection vulnerability. CWE is classifying the issue as CWE-74. The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

CGI versions before 5.00 for Perl allow HTTP header injection via entity decoding after the newline check in header and unchecked values in multipart_start and do_push. With autoEscape off, header decodes HTML entities in extra header values after its newline check, so an encoded CR or LF reaches the response. multipart_start does not check header values for newlines, and do_push does not check the type it prints in each part. An application that passes request data into these header values can be made to add headers or split the response.

The advisory is shared at metacpan.org. This vulnerability is uniquely identified as CVE-2026-120639 since 11/02/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1055 for this issue.

Upgrading to version 5.00 eliminates this vulnerability.

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Productinfo

Vendor

CPANSec

Name

Version

CPE 2.3info

🔒

CPE 2.2info

🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.3
VulDB Meta Temp Score: 7.0

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
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💳	💳	💳	💳	💳	💳
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Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Injection
CWE: CWE-74 / CWE-707 / CWE-20
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: CGI 5.00

Timelineinfo

11/02/2026 CVE reserved
11/04/2026 +2 days Advisory disclosed
11/04/2026 +0 days VulDB entry created
11/04/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: metacpan.org
Status: Confirmed

CNA: CPANSec
CVE: CVE-2026-120639 (🔒)

GCVE (CVE): GCVE-0-2026-120639
GCVE (VulDB): GCVE-100-430917

Entryinfo

Created: 11/04/2026 01:13
Changes: 11/04/2026 01:13 (56)
Complete: 🔍
Cache ID: 216::103