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Fencer Vulns
high 7.5

CVE-2026-28435 json

Payload size limit bypass via gzip decompression in ContentReader (streaming) allows oversized request bodies in cpp-httplib

published 2026-03-04 8 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-9496

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 41%
public exploits
0
none known

Summary

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.35.0, cpp-httplib (httplib.h) does not enforce Server::set_payload_max_length() on the decompressed request body when using HandlerWithContentReader (streaming ContentReader) with Content-Encoding: gzip (or other supported encodings). A small compressed payload can expand beyond the configured payload limit and be processed by the application, enabling a payload size limit bypass and potential denial of service (CPU/memory exhaustion). This vulnerability is fixed in 0.35.0.

Patch / fix

  • cpp-httplib_project cpp-httplib 0.35.0
  • yhirose cpp-httplib 0.35.0
  • cpp-httplib Debian 14 0.41.0+ds-3

debian advisories DEBIAN-CVE-2026-28435

  • cpp-httplib openSUSE Tumbleweed 0.38.0-1.1

opensuse advisories openSUSE-SU-2026:10435-1

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-2026-28435 updated cvss 7.5

cpp-httplib: payload size limit bypass via gzip decompression in ContentReader (streaming) allows oversized request bodies

  • 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
8 mo ago

Exploit prediction

0.48% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-xvfx-w463-6fpp referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

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

Affected products

  • yhirose cpp-httplib

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)

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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.