Cpp Httplib
CVE-2026-31870
HIGH
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessAttacker controls HTTP server
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DeliveryClient uses streaming API to connect
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ExploitServer responds with malformed Content-Length header
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Executionstd::stoull() throws unhandled exception
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ImpactProcess terminates with SIGABRT
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A10:2025 - Mishandling of Exceptional Conditions
ASVS 5.0
V16 - Security Logging and Error Handling Exception handling completeness
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| Exploitation Conditions | Application must use cpp-httplib streaming API functions (httplib::stream::Get, httplib::stream::Post, etc.) to connect to attacker-controlled or compromised HTTP server. No authentication required; exploit triggers on any streaming request receiving malicious Content-Length header value. |
| Impact | CVSS 7.5 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: None. User interaction: None. Exploitation no authentication required. |
| Exploit ScenarioDerived | An attacker without authentication could exploit this vulnerability to compromise the affected system. |
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Alert meAnalysisAIv1 – Mar 12, 2026
cpp-httplib versions prior to 0.37.1 crash when the streaming API receives a malformed Content-Length header from any server, as the library fails to validate or handle exceptions from the underlying string parsing function. An attacker can exploit this denial of service condition by hosting a malicious server, performing a man-in-the-middle attack, or leveraging HTTP redirects to crash any client application using the vulnerable library. Currently no patch is available for this issue.
Earlier versions of this analysis (1)
single-file header-only cross platform HTTP/HTTPS library. versions up to 0.37.1 contains a security vulnerability (CVSS 7.5).
RemediationAI
Fixed in version 0.37.1.. Restrict network access to the affected service where possible.
Affects your stack
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Technical ContextAI · show details
affects single-file header-only cross platform HTTP/HTTPS library.. cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.37.1, when a cpp-httplib client uses the streaming API (httplib::stream::Get, httplib::stream::Post, etc.), the library calls std::stoull() directly on the Content-Length header value received from the server with no input validation and no exception handling. std::stoull throws std::invalid_argument for non-numeric strings and std::out_of_range for values exceeding ULLONG_MAX. Since nothing catches thes
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Primary rating from GitHub Advisory.
CVSS VectorGitHub Advisory
DescriptionGitHub Advisory
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.37.1, when a cpp-httplib client uses the streaming API (httplib::stream::Get, httplib::stream::Post, etc.), the library calls std::stoull() directly on the Content-Length header value received from the server with no input validation and no exception handling. std::stoull throws std::invalid_argument for non-numeric strings and std::out_of_range for values exceeding ULLONG_MAX. Since nothing catches these exceptions, the C++ runtime calls std::terminate(), which kills the process with SIGABRT. Any server the client connects to - including servers reached via HTTP redirects, third-party APIs, or man-in-the-middle positions can crash the client application with a single HTTP response. No authentication is required. No interaction from the end user is required. The crash is deterministic and immediate. This vulnerability is fixed in 0.37.1.
Executive ViewAI
Applications using cpp-httplib's streaming API are vulnerable to denial-of-service attacks when processing malformed HTTP responses from untrusted servers. An attacker can craft responses with invalid Content-Length headers that crash client applications, potentially disrupting dependent services and user availability.
Disable streaming API (httplib::stream::Get, httplib::stream::Post) if not critical to operations; implement network segmentation to restrict which servers applications can connect to; deploy WAF or proxy rules to validate and sanitize Content-Length headers before they reach client applications; wrap streaming calls with exception handling to catch std::invalid_argument and prevent application crashes; monitor for unexpected application crashes correlated with external HTTP communications.
Threat Intelligence Overview
NVD
CVE.org
EPSS
GitHub
VulDB
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.
Affected Products (CPE)GitHub Advisory
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View allVendor StatusVendor
SUSE
Severity: High| Product | Status |
|---|---|
| SUSE Linux Enterprise Server 16.0 | Fixed |
| SUSE Linux Enterprise Server 16.1 | Fixed |
| SUSE Linux Enterprise Server for SAP applications 16.0 | Fixed |
| SUSE Linux Enterprise Server for SAP applications 16.1 | Fixed |
Exploit-DB