CVE-2024-23829

Security-sensitive parts of the Python HTTP parser retained minor differences in allowable character sets, that must trigger error handling to robustly match frame boundaries of proxies in order to protect against injection of additional requests. Additionally, validation could trigger exceptions that were not handled consistently with processing of other malformed input.

Details

These problems are rooted in pattern matching protocol elements, previously improved by PR #3235 and GHSA-gfw2-4jvh-wgfg:

1. The expression HTTP/(\d).(\d) lacked another backslash to clarify that the separator should be a literal dot, not just any Unicode code point (result: HTTP/(\d)\.(\d)).

2. The HTTP version was permitting Unicode digits, where only ASCII digits are standards-compliant.

3. Distinct regular expressions for validating HTTP Method and Header field names were used - though both should (at least) apply the common restrictions of rfc9110 token.

PoC

GET / HTTP/1ö1
GET / HTTP/1.𝟙
GET/: HTTP/1.1
Content-Encoding?: chunked

Primarily concerns running an aiohttp server without llhttp:

1. behind a proxy: Being more lenient than internet standards require could, depending on deployment environment, assist in request smuggling.
2. directly accessible or exposed behind proxies relaying malformed input: the unhandled exception could cause excessive resource consumption on the application server and/or its logging facilities.

Patch: https://github.com/aio-libs/aiohttp/pull/8074/files

CVE-2024-23829 has a CVSS score of 6.5 (Medium). 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 (3.9.2); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2024-23829? CVE-2024-23829 is a medium-severity security vulnerability in aiohttp (pip), affecting versions < 3.9.2. It is fixed in 3.9.2.
2. How severe is CVE-2024-23829? CVE-2024-23829 has a CVSS score of 6.5 (Medium). 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 aiohttp are affected by CVE-2024-23829? aiohttp (pip) versions < 3.9.2 is affected.
4. Is there a fix for CVE-2024-23829? Yes. CVE-2024-23829 is fixed in 3.9.2. Upgrade to this version or later.
5. Is CVE-2024-23829 exploitable, and should I be worried? Whether CVE-2024-23829 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-2024-23829 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-2024-23829? Upgrade aiohttp to 3.9.2 or later.

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