What’s Vulnerable › Vulnerabilities

CVE-2023-34188

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.0% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-06-23 · updated 2026-06-17
• Weakness: CWE-1284

Description

The HTTP server in Mongoose before 7.10 accepts requests containing negative Content-Length headers. By sending a single attack payload over TCP, an attacker can cause an infinite loop in which the server continuously reparses that payload, and does not respond to any other requests.

Affected products

• Cesanta Mongoose: before 7.10 — fixed in 7.10

How to fix

Upgrade to a fixed version: Cesanta Mongoose 7.10. Check the vendor advisory for mitigations.

References

• https://blog.narfindustries.com/blog/narf-discovers-critical-vulnerabilities-in-cesanta-mongoose-http-server
• https://github.com/cesanta/mongoose/commit/4663090a8fb036146dfe77718cff612b0101cb0f
• https://github.com/cesanta/mongoose/compare/7.9...7.10
• https://github.com/cesanta/mongoose/pull/2197
• https://blog.narfindustries.com/blog/narf-discovers-critical-vulnerabilities-in-cesanta-mongoose-http-server
• https://github.com/cesanta/mongoose/commit/4663090a8fb036146dfe77718cff612b0101cb0f
• https://github.com/cesanta/mongoose/compare/7.9...7.10
• https://github.com/cesanta/mongoose/pull/2197
• https://security.netapp.com/advisory/ntap-20250228-0001/

Get alerted when CVE-2023-34188 or the next vulnerability affects your stack