CVE-2026-22776
Yhirose Cpp-Httplib ≤ 0.30.1
Raw vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:XSummary
CVE-2026-22776 is a high-severity Data Amplification (CWE-409) vulnerability in Yhirose Cpp-Httplib. Its CVSS base score is 8.7 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Endpoint Denial of Service (T1499); ranked at the 29th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and SC-5 (Denial-of-service Protection) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-22776 is a Denial of Service (DoS) vulnerability in cpp-httplib, a C++11 single-file header-only cross-platform HTTP/HTTPS library. The issue affects versions prior to 0.30.1 and stems from unsafe handling of compressed HTTP request bodies using Content-Encoding such as gzip or br. Specifically, the library enforces the payload_max_length limit only against the size of the compressed data received from the network, without restricting the size of the decompressed data allocated in memory. This flaw is rated at CVSS 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) and maps to CWE-409 (Improper Handling of Highly Compressed Data).
An attacker can exploit this vulnerability remotely over the network with low complexity, requiring no privileges or user interaction. By sending a malicious HTTP request with a small compressed body that expands significantly upon decompression—such as a gzip-encoded payload—the attacker can force the server to allocate excessive memory. This leads to memory exhaustion, potential out-of-memory crashes, or severe degradation of service availability on affected cpp-httplib-based HTTP servers.
Mitigation is available via the patch in cpp-httplib version 0.30.1, detailed in the fix commit at https://github.com/yhirose/cpp-httplib/commit/2e2e47bab1ae6a853476eecbc4bf279dd1fef792. The GitHub security advisory at https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-h934-98h4-j43q provides further guidance, recommending immediate upgrades for applications using vulnerable versions.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-2006
Vulnerability Data
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.30.1, a Denial of Service (DoS) vulnerability exists in cpp-httplib due to the unsafe handling of compressed HTTP request bodies (Content-Encoding: gzip, br, etc.). The library validates…
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the payload_max_length against the compressed data size received from the network, but does not limit the size of the decompressed data stored in memory.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Input validation can reject or limit decompression of data whose expansion ratio exceeds safe thresholds.
DoS protection limits the resource-exhaustion impact when a decompression bomb is processed.
Resource allocation controls bound memory/CPU consumption that a data-amplification attack would otherwise exhaust.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure-development practices include input-validation and resource-limit checks that prevent improper handling of compressed data.
Runtime monitoring of compute resources can detect exhaustion caused by decompression bombs.
Capacity planning and monitoring directly limits the availability impact of data-amplification attacks.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can uncover decompression-bomb vulnerabilities before release.
Redundancy helps availability but does not address the root cause of the weakness.
Monitoring can detect anomalous resource usage but does not prevent the weakness.
Secure development lifecycle includes input validation and resource-limit checks that mitigate data-amplification attacks.
Application security requirements can mandate limits on decompression size and ratio.
Secure architecture principles encourage defensive design against resource-exhaustion threats.