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CVE-2026-45372

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

Published: May 29, 2026Updated: May 29, 2026 Sources: CVE List NVD
NVD MITRE
9.9CVSS
CRITICAL

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.

EPSS Score
0.0%
Top 87.1%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:CC:LI:HA:L
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:CScope
Changed
Impact
C:LConfidentiality
Low
I:HIntegrity
High
A:LAvailability
Low

Weaknesses

CWE-93CWE-444

Affected Products

cpp-httplib
yhirose

Attack Graph

Products CVE Techniques Tactics

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Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

MITRE ATT&CK

1 technique
Collection
View detailed technique mapping

References

https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-xjxg-64p4-vj4m
github.com

Timeline

Published
May 29, 2026
Last Updated
May 29, 2026

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