# 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.

- **Severity:** High 7.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 29 Aug 2025
- **Updated:** 29 Aug 2025
- **Also known as:** DEBIAN-CVE-2025-40927, GHSA-wh29-fq99-4ww5, UBUNTU-CVE-2025-40927, openSUSE-SU-2025:15625-1

## 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 (Improper Neutralization of CRLF Sequences in HTTP Headers)

## Which versions are affected by CVE-2025-40927?


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `perl-CGI-Simple` | openSUSE:Tumbleweed | All versions | 1.282.0-1.1 |

## How do I fix CVE-2025-40927?

Upgrade to a fixed version.

## Is CVE-2025-40927 being exploited?

There is no known exploitation of CVE-2025-40927 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40927 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2025-40927 in the wild and no public exploit code.

Affected product: MANWAR CGI::Simple. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-40927/ (Markdown: https://insights.sbomify.com/CVE-2025-40927/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40927
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40927
- OSV: https://osv.dev/vulnerability/CVE-2025-40927

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40927/
Summaries are generated and may contain mistakes; the official description above is the record.