Quick answers
- Is CVE-2026-120638 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-120638 being exploited in the wild.
- How severe is CVE-2026-120638?
- Informational severity, published 4 November 2026.
- Which products and versions are affected?
- Perl CGI before 5.00.
- Is there a fix for CVE-2026-120638?
- Yes: fixed in CGI 5.00. Until then: Do not pass HTML-encoded redirect URLs to the redirect() function; applications must pass unescaped values and handle URL encoding separately at the HTTP layer. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-120638 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-120638?
- Check whether you run Perl CGI at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- Fixed in: CGI 5.00
Do not pass HTML-encoded redirect URLs to the redirect() function; applications must pass unescaped values and handle URL encoding separately at the HTTP layer.
Technical details
The redirect() function in CGI.pm, as well as header() and multipart_start(), perform HTML entity decoding on their arguments including Location headers and redirect URLs. This occurs after application-level validation, allowing an attacker to supply encoded entities that decode to dangerous URLs after validation passes. An unauthenticated network attacker can craft a link with HTML-encoded redirect parameters to perform phishing or credential theft attacks.
Affected products
- Perl CGI before 5.00
Timeline
- 2026-11-04: disclosed