CVE-2025-40927 CGI::Simple versions 1.281 and earlier for Perl has a HTTP response splitting flaw
Attackers can inject HTTP headers via URL-encoded newlines in CGI::Simple, enabling reflected XSS and open redirects.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-40927?
CVE-2025-40927 is a high-severity cross-site scripting vulnerability in MANWAR CGI::Simple, published on 29 Aug 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
CGI::Simple versions before 1.282 for Perl has a HTTP response splitting flaw This vulnerability is a confirmed HTTP response splitting flaw in CGI::Simple that allows HTTP response header injection, which can be used for reflected XSS or open redirect under certain conditions.
Although some validation exists, it can be bypassed using URL-encoded values, allowing an attacker to inject untrusted content into the response via query parameters.
As a result, an attacker can inject a line break (e.g. %0A) into the parameter value, causing the server to split the HTTP response and inject arbitrary headers or even an HTML/JavaScript body, leading to reflected cross-site scripting (XSS), open redirect or other attacks.
The issue documented in CVE-2010-4410 https://www.cve.org/CVERecord?id=CVE-2010-4410 is related but the fix was incomplete.
Impact
By injecting %0A (newline) into a query string parameter, an attacker can:
* Break the current HTTP header * Inject a new header or entire body * Deliver a script payload that is reflected in the server’s response That can lead to the following attacks:
* reflected XSS * open redirect * cache poisoning * header manipulation
Weakness: CWE-113
Which versions are affected by CVE-2025-40927?
Linux distribution packages (1)
perl-CGI-Simple openSUSE:Tumbleweed | All versions | 1.282.0-1.1 |
How do I fix CVE-2025-40927?
Upgrade to a fixed version.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2025-40927 being exploited?
There is no known exploitation of CVE-2025-40927 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2025-40927, GHSA-wh29-fq99-4ww5, UBUNTU-CVE-2025-40927, openSUSE-SU-2025:15625-1.