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Vulnerabilities

Vulnerability · CVE-2026-103930

cpp-httplib is a C++ header-only HTTP/HTTPS library.

Published Oct 14, 2026 · catalog updated Oct 15, 2026 · cpp-httplib is a C++

Check if you run it

No confirmed exploitation is on record for CVE-2026-103930. EPSS is 0.37%. Act only if a listed version of cpp-httplib is a C++ is installed.

Severity
Low3.7
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.37%
Remediation
Advisory link
Affected products
See sources for product scope

cpp-httplib is a C++ header-only HTTP/HTTPS library. From 0.29.0 until 0.51.0, Client::open_stream in httplib.h accepts a caller-controlled path that reaches detail::write_request_line() without the detail::encode_path() protection used by the ordinary buffered request path. Raw carriage-return and line-feed bytes in the path can therefore split the outbound HTTP/1.1 request line and inject attacker-shaped request metadata. Exploitation requires an embedding application to pass remote user input into the open_stream path and a backend or intermediary that interprets the injected bytes; the established impact is modification of backend-visible request data, not direct confidentiality or availability impact. This issue is fixed in version 0.51.0.

No affected version ranges are stored yet. Use the vendor advisory before you decide this record does not apply.

How to fix CVE-2026-103930

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-103930. EPSS is 0.37%. Act only if a listed version of cpp-httplib is a C++ is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-113. EPSS 0.37%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 14, 2026 · NIST NVD

    Detected

    cpp-httplib is a C++ header-only HTTP/HTTPS library. From 0.29.0 until 0.51.0, Client::open_stream in httplib.h accepts a caller-controlled path that reaches detail::write_request_line() without the detail::encode_path() protection used by the ordinary buffered request path. Raw carriage-return and line-feed bytes in the path can therefore split the outbound HTTP/1.1 request line and inject attack

  2. Oct 15, 2026 · NIST NVD

    Updated

    cpp-httplib is a C++ header-only HTTP/HTTPS library. From 0.29.0 until 0.51.0, Client::open_stream in httplib.h accepts a caller-controlled path that reaches detail::write_request_line() without the detail::encode_path() protection used by the ordinary buffered request path. Raw carriage-return and line-feed bytes in the path can therefore split the outbound HTTP/1.1 request line and inject attack

Sources

  • CVE.orgVulnerability recordCVE-2026-103930

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-103930

    30-day exploitation probability 0.4%

    first.org
  • NIST NVDVulnerability recordCVE-2026-103930

    cpp-httplib is a C++ header-only HTTP/HTTPS library. From 0.29.0 until 0.51.0, Client::open_stream in httplib.h accepts a caller-controlled path that reaches detail::write_request_line() without the detail::encode_path() protection used by the ordinary buffered request path. Raw

    nvd.nist.gov
  • OpenCVEVendor advisoryCVE-2026-103930

    CVE-2026-103930 is named on the public OpenCVE page.

    opencve.io

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.