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TI-2026-33163 Aliases CVE-2026-45372

cpp-httplib: HTTP header value percent-decoding in server-side `parse_header` enables CRLF injection

Priority HIGH 82CWE-444Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
Low · High · Low
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.44.0, when cpp-httplib's server parses an incoming request, it applies percent-decoding to every header value except Location and Referer. The validity check (is_field_value) is run before decoding, so encoded %0D%0A passes the check and is then expanded to a literal \r\n byte pair inside the stored header value. This vulnerability is fixed in 0.44.0.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00295 22nd percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed cpp-httplib (yhirose): 0.44.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
yhirosecpp-httplibbefore 0.44.00.44.0Patch availableCNA
  • cpp-httplib Vendoryhirose Affected before 0.44.0 Fixed in 0.44.0 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:yhirose:cpp-httplib:*:*:*:*:*:*:*:*before 0.44.0Vulnerableyhirose
  • cpe:2.3:a:yhirose:cpp-httplib:*:*:*:*:*:*:*:* Versions before 0.44.0 Vulnerable ·yhirose

Remediation

  • Fix · CNA cpp-httplib (yhirose) Fixed in 0.44.0

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-45372

References

Exploit 1

  • TI-2026-18294 cpp-httplib vulnerable to a denial of service (DOS) using a zip bomb CVSS 4.0HIGH 8.7
  • TI-2026-17313 cpp-httplib has CRLF injection in http headers CVSS 4.0HIGH 7.7
  • TI-2026-33146 cpp-httplib DoS: Negative chunk-size in chunked Transfer-Encoding CVSS 3.1HIGH 7.5
  • TI-2026-22709 Uncontrolled resource consumption in yhirose cpp-httplib CVSS 3.1HIGH 7.5
  • TI-2025-33556 cpp-httplib Unbounded Memory Allocation in Chunked/No-Length Requests Vulnerability CVSS 3.1HIGH 7.5
  • TI-2025-32923 cpp-httplib has unlimited number of http header fields, which causes memory leak CVSS 3.1HIGH 7.5
See all 19 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences