CVE-2025-40927 (CVSS 7.3)

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

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CVSS v3.1 Score

7.3

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Weakness Type (CWE)

CWE-113 CWE-113

References

Other References

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2004-2320 https://datatracker.ietf.org/doc/html/rfc7230#section-3 https://metacpan.org/release/MANWAR/CGI-Simple-1.281/diff/MANWAR/CGI-Simple-1.282/lib/CGI/Simple.pm https://metacpan.org/release/MANWAR/CGI-Simple-1.281/source/lib/CGI/Simple.pm#L1031-1035 https://owasp.org/www-community/attacks/HTTP_Response_Splitting https://rt.perl.org/Public/Bug/Display.html?id=21951

Frequently Asked Questions

What is CVE-2025-40927? +

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 It has a CVSS v3.1 base score of 7.3 (HIGH).

How severe is CVE-2025-40927? +

CVE-2025-40927 has a CVSS v3.1 score of 7.3 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

How do I check if I'm vulnerable to CVE-2025-40927? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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