CVE-2026-120640: CGI versions before 5.00 for Perl allow the POSTDATA, PUTDATA, PATCHDATA and XForms:Model parameters to be set from the query string or form fields
CVE-2026-120640 is a vulnerability in CGI versions before 5.00 for Perl allow the POSTDATA, PUTDATA, PATCHDATA and XForms:Model parameters to be set from the query string or form fields, rated Important by Microsoft, with a CVSS 3.1 base score of 9.1 (Critical). An attacker can exploit it remotely over the network, without any privileges and without user interaction. Microsoft has not reported exploitation in the wild. The EPSS model estimates a 0.13% probability of exploitation activity in the next 30 days, higher than 3% of all scored vulnerabilities. Microsoft released the fix on 7 November 2026, outside Patch Tuesday. It affects 1 product in 1 product family (Open Source Software).
Key facts
- CVE ID
- CVE-2026-120640
- Severity
- Critical CVSS 9.1
- Microsoft severity
- Important
- Exploited in the wild
- No
- Publicly disclosed
- No
- EPSS
- 0.13% (percentile 3%)
- CISA KEV
- Not listed
- Released
- Last updated
- Patch Tuesday
- November 2026 Patch Tuesday
- Product families
- Open Source Software
CVSS score and vector
Microsoft scores CVE-2026-120640 at 9.1 (temporal 8.3) using CVSS 3.1. Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N/E:U
| Metric | Value |
|---|---|
| Attack vector | Network |
| Attack complexity | Low |
| Privileges required | None |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality impact | High |
| Integrity impact | High |
| Availability impact | None |
| Exploit code maturity | Unproven |
Affected products (1)
Open Source Software
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| azl3 perl-CGI 4.60-1 on Azure Linux 3.0 | Release Notes | Security Update |
Revision history
| Version | Date | Description |
|---|---|---|
| 1.0 | Information published. |