CVE-2023-29530

HTTP Multiline Header Termination

Workarounds

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().

References

• CVE-2023-29197
• GHSA-wxmh-65f7-jcvw

Affected versions of Laminas Diactoros accepted a single line feed (LF / \n ) character at the end of a header name. When serializing such a header name containing a line-feed into the on-the-wire representation of a HTTP/1.x message, the resulting message would be syntactically invalid, due to the header line being terminated too early. An attacker that is able to control the header names that are passed to Laminas Diactoros 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 application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

CVE-2023-29530 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.18.1, 2.19.1, 2.20.1, 2.21.1, 2.22.1, 2.23.1, 2.24.2, 2.25.2); upgrading removes the vulnerable code path.

Kodem intelligence

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The problem has been patched in the following versions:

• 2.18.1
• 2.19.1
• 2.20.1
• 2.21.1
• 2.22.1
• 2.23.1
• 2.24.2
• 2.25.2

1. What is CVE-2023-29530? CVE-2023-29530 is a high-severity improper input validation vulnerability in laminas/laminas-diactoros (composer), affecting versions < 2.18.1. It is fixed in 2.18.1, 2.19.1, 2.20.1, 2.21.1, 2.22.1, 2.23.1, 2.24.2, 2.25.2. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. How severe is CVE-2023-29530? CVE-2023-29530 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of laminas/laminas-diactoros are affected by CVE-2023-29530? laminas/laminas-diactoros (composer) versions < 2.18.1 is affected.
4. Is there a fix for CVE-2023-29530? Yes. CVE-2023-29530 is fixed in 2.18.1, 2.19.1, 2.20.1, 2.21.1, 2.22.1, 2.23.1, 2.24.2, 2.25.2. Upgrade to this version or later.
5. Is CVE-2023-29530 exploitable, and should I be worried? Whether CVE-2023-29530 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2023-29530 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2023-29530?
   • Upgrade laminas/laminas-diactoros to 2.18.1 or later
   • Upgrade laminas/laminas-diactoros to 2.19.1 or later
   • Upgrade laminas/laminas-diactoros to 2.20.1 or later
   • Upgrade laminas/laminas-diactoros to 2.21.1 or later
   • Upgrade laminas/laminas-diactoros to 2.22.1 or later
   • Upgrade laminas/laminas-diactoros to 2.23.1 or later
   • Upgrade laminas/laminas-diactoros to 2.24.2 or later
   • Upgrade laminas/laminas-diactoros to 2.25.2 or later

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