CVE-2026-21428

HIGH EPSS 29.0%
Published Jan 1, 20266mo ago · Modified Jun 17, 20261w ago
7.7 CVSS 4.0
High
Find Similar
Published Jan 1, 2026 6mo ago
Last Modified Jun 17, 2026 1w ago

Description

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.30.0, the ``write_headers`` function does not check for CR & LF characters in user supplied headers, allowing untrusted header value to escape header lines. This vulnerability allows attackers to add extra headers, modify request body unexpectedly & trigger an SSRF attack. When combined with a server that supports http1.1 pipelining (springboot, python twisted etc), this can be used for server side request forgery (SSRF). Version 0.30.0 fixes this issue.

CVSS Details

Base Score
7.7
Exploitability
—
Impact
—
Vector string
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope X

Threat Intelligence

EPSS Exploit Probability
29.0% percentile
Exploit & Patch Status
Public Exploit Known
Patch Available

Weaknesses 1

CWE-93

Affected Products 1

VendorProductVersionRange
yhirosecpp-httplib* <0.30.0

References 3

  • github.com https://github.com/yhirose/cpp-httplib/commit/98048a033a532ff22320ce1d11789f8d5710dfcd
    Patch
  • github.com https://github.com/yhirose/cpp-httplib/releases/tag/v0.30.0
    ProductRelease Notes
  • github.com https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-wpc6-j37r-jcx7
    ExploitThird Party Advisory

Remediation

  • github.com https://github.com/yhirose/cpp-httplib/commit/98048a033a532ff22320ce1d11789f8d5710dfcd
    Patch