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Security Advisories: GSA_kwCzR0hTQS1xMnFqLTYyOGctdmhmd84AAy3N

Insecure header validation in slim/psr7


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.


The issue is patched in 1.6.1, 1.5.1, and 1.4.1.


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().


We are very grateful to and thank Graham Campbell for reporting and working with us on this issue.


Source: GitHub Advisory Database
Origin: Unspecified
Severity: Moderate
Classification: General
Published: about 1 year ago
Updated: 7 months ago

CVSS Score: 6.5
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Identifiers: GHSA-q2qj-628g-vhfw, CVE-2023-30536
References: Repository:
Blast Radius: 21.8

Affected Packages

Dependent packages: 354
Dependent repositories: 2,242
Downloads: 8,327,663 total
Affected Version Ranges: < 1.4.1, >= 1.5, < 1.5.1, >= 1.6, < 1.6.1
Fixed in: 1.4.1, 1.5.1, 1.6.1
All affected versions: 0.1.0, 0.2.0, 0.3.0, 0.4.0, 0.5.0, 1.0.0, 1.1.0, 1.2.0, 1.3.0
All unaffected versions: 1.4.1, 1.5.1, 1.6.1