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Fencer Vulns
high 7.5

CVE-2023-34188 json

The HTTP server in Mongoose before 7.10 accepts requests containing negative Content-Length headers.

published 2023-06-23 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-38288

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.0%
EPSS 1.0% chance of exploitation in 30 days, percentile 63%
public exploits
0
none known

Summary

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.

Patch / fix

  • cesanta mongoose 7.10
  • swupdate Debian 14, Debian 13 2024.12+dfsg-1

debian advisories DEBIAN-CVE-2023-34188

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-34188 updated cvss 5.5

mongoose: Added check for negative value for HTTP Content-Length header

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
23 mo ago

Exploit prediction

1.00% chance of exploitation in the next 30 days, higher than 63% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Classification

Weakness
  • CWE-1284 Improper Validation of Specified Quantity in Input

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.