CVE-2026-34441
mediumcpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.40.0, cpp-httplib is vulnerable to HTTP Request Smuggling. The server's static file handler serves GET responses without consuming the request body. On HTTP/1.1 keep-alive connections, the unread body bytes remain on the TCP stream and are interpreted as the start of a new HTTP request. An attacker can embed an arbitrary HTTP request inside the body of a GET request, which the server processes as a separate request. This issue has been patched in version 0.40.0.
4.8
cvss
medium
common vulnerability scoring system v3.1. measures intrinsic severity on a 0-10 scale.
epss
0.0003
kev
no
cisa known exploited vulnerabilities catalog. confirmed active exploitation.
CVSS 3.1
Common Vulnerability Scoring System v3.1
4.8
/ 10
MEDIUM
exploitability
Attack Vector
Network
Attack Vector (AV:N): exploitable remotely over the network — most dangerous. no physical or adjacent access needed.
Attack Complexity
High
Attack Complexity (AC:H): exploitation requires specific conditions outside the attacker's control (race condition, non-default config, etc).
Privileges Required
None
Privileges Required (PR:N): no authentication needed. any anonymous attacker can exploit this.
User Interaction
None
User Interaction (UI:N): no victim action needed. fully exploitable without user interaction.
impact
Scope
Unchanged
Scope (S:U): impact limited to the vulnerable component.
Confidentiality
Low
Confidentiality (C:L): limited data exposure. some restricted information can be read.
Integrity
Low
Integrity (I:L): limited data modification. some data can be altered.
Availability
None
Availability (A:N): no availability impact.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
activity density
rdintel assessment
composite score from 15+ signals including exploitation status, epss probability, detection coverage, and community attention. 0-100 scale.
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