Quick answers
- Is CVE-2026-120643 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-120643 being exploited in the wild.
- How severe is CVE-2026-120643?
- Informational severity, published 4 November 2026.
- Which products and versions are affected?
- Perl CGI 4.62 before 5.00.
- Is there a fix for CVE-2026-120643?
- Yes: fixed in 5.00. Until then: Ensure that any URL returned by url() or self_url() is properly HTML-escaped before being placed in HTML attributes or JavaScript strings, even if single quotes are percent-encoded.</anigation> </invoke> Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-120643 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-120643?
- 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: 5.00
Ensure that any URL returned by url() or self_url() is properly HTML-escaped before being placed in HTML attributes or JavaScript strings, even if single quotes are percent-encoded.</anigation> </invoke>
Technical details
The url() and self_url() functions pass URLs through URI::canonical(), which decodes percent-encoded unreserved characters including %27 (single quote) back to raw apostrophes. An apostrophe in the request path or query parameters remains unescaped in the output, allowing an attacker to inject a raw quote character. If an application embeds the returned URL in a single-quoted HTML attribute or JavaScript string without additional escaping, the attacker can break out and inject arbitrary code. The fix percent-encodes single quotes after canonicalization to prevent this breakout.
Affected products
- Perl CGI 4.62 before 5.00