CVE-2026-31870: high-severity vulnerability in yhirose cpp-httplib
cpp-httplib Affected by Remote Process Crash via Malformed Content-Length Response Header
Published · Updated
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.5epss 0.5%
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected products
yhirose · cpp-httplibRelated CVEs — yhirose cpp-httplib
In the same product, most dangerous first.
CVE-2025-46728HIGHcpp-httplib has Unbounded Memory Allocation in Chunked/No-Length RequestsEPSS 0.7%CVE-2026-29076MEDIUMcpp-httplib: Stack Overflow Denial of Service (DoS) via std::regex in multipart filename parsingEPSS 0.6%CVE-2025-53629HIGHcpp-httplib Unbounded Memory Allocation in Chunked/No-Length Requests VulnerabilityEPSS 0.6%CVE-2025-53628MEDIUMcpp-httplib does not limit the length of a lineEPSS 0.5%CVE-2025-52887HIGHcpp-httplib has unlimited number of http header fields, which causes memory leakEPSS 0.5%CVE-2026-28435HIGHPayload size limit bypass via gzip decompression in ContentReader (streaming) allows oversized request bodies in cpp-httplibEPSS 0.5%