Insecure header validation in slim/psr7
Impact
An attacker could sneak in a newline (\n) into both the header names and values. While the specification states that \r\n\r\n is used to terminate the header list, many servers in the wild will also accept \n\n. An attacker that is able to control the header names that are passed to Slilm-Psr7 would be able to intentionally craft invalid messages, possibly causing application errors or invalid HTTP requests being sent out with an PSR-18 HTTP client. The latter might present a denial of service vector if a remote service’s web application firewall bans the application due to the receipt of malformed requests.
Patches
The issue is patched in 1.6.1, 1.5.1, and 1.4.1.
Workarounds
In Slim-Psr7 prior to 1.6.1, 1.5.1, and 1.4.1, validate HTTP header keys and/or values, and if using user-supplied values, filter them to strip off leading or trailing newline characters before calling withHeader().
Acknowledgments
We are very grateful to and thank <a href="https://gjcampbell.co.uk/">Graham Campbell</a> for reporting and working with us on this issue.
References
- Guzzle: CVE-2023-29197, with advisory GHSA-wxmh-65f7-jcvw
- Laminas Diactoros: CVE-2023-29530, with advisory GHSA-xv3h-4844-9h36
- https://www.rfc-editor.org/rfc/rfc7230#section-3.2.4
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Composer package | slim/psr7 | >= 1.6, < 1.6.1, >= 1.5, < 1.5.1, < 1.4.1 | 1.6.1, 1.5.1, 1.4.1 |
References
- https://github.com/slimphp/Slim-Psr7/security/advisories/GHSA-q2qj-628g-vhfw
- https://nvd.nist.gov/vuln/detail/CVE-2023-30536
- https://github.com/slimphp/Slim-Psr7/issues/284#issuecomment-1541328898
- https://github.com/slimphp/Slim-Psr7/commit/ed1d553225dd190875d8814c47460daed4b550bb
- https://github.com/slimphp/Slim-Psr7
- https://github.com/slimphp/Slim-Psr7/releases/tag/1.4.1
- https://github.com/slimphp/Slim-Psr7/releases/tag/1.5.1
- https://github.com/slimphp/Slim-Psr7/releases/tag/1.6.1
- https://www.rfc-editor.org/rfc/rfc7230#section-3.2.4
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L- Weakness (CWE)
CWE-436- Platform
- Composer
- Package
slim/psr7- Disclosed
- 18.04.2023
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-q2qj-628g-vhfw - CC BY 4.0
Vulnerability history: slim/psr7
All published vulnerabilities of this package (Composer package), newest first. Shows whether this is a one-off slip or a package that needs watching.
This is the only known vulnerability of this package.
Know which vulnerabilities affect your application
With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.