CGI::Simple versions 1.281 and earlier for Perl has a HTTP response splitting flaw
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- Low · Low · Low
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA.
Summary
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
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
- Fix · CNA CGI::Simple (MANWAR) Fixed in 1.282
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2025-40927
- 2026-10-03 Alias added: GHSA-wh29-fq99-4ww5
References
Other 6
- https://metacpan.org/release/MANWAR/CGI-Simple-1.281/source/lib/CGI/Simple.pm#L1031-1035
- https://metacpan.org/release/MANWAR/CGI-Simple-1.281/diff/MANWAR/CGI-Simple-1.282/lib/CGI/Simple.pm
- https://owasp.org/www-community/attacks/HTTP_Response_Splitting
- https://datatracker.ietf.org/doc/html/rfc7230#section-3
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2004-2320
- https://rt.perl.org/Public/Bug/Display.html?id=21951
Sources
- CVE-2025-40927 · CVE Program
- CVE-2025-40927 · NVD
- FIRST EPSS
- GHSA-wh29-fq99-4ww5 · GitHub Advisory Database · CC BY 4.0
- CVE-2025-40927 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences