CVE-2026-21428

EPSS 0.0%
  • Published: 2026-01-01T18:15:41.057

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.30.0, the “write_headers“ function does not check for CR & LF characters in user supplied headers, allowing untrusted header value to escape header lines.
This vulnerability allows attackers to add extra headers, modify request body unexpectedly & trigger an SSRF attack. When combined with a server that supports http1.1 pipelining (springboot, python twisted etc), this can be used for server side request forgery (SSRF). Version 0.30.0 fixes this issue.

Related CVE by CWE

No related CWE found.

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Recently Exploited Similar Vulnerabilities

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How to fix CVE-2026-21428

CVE-2026-21428 is a unknown severity vulnerability affecting the affected product.

Description: cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.30.0, the “write_headers“ function does not check for CR & LF characters in user supplied headers, allowing untrusted header value to escape header lines. This vulnerability allows attackers to add extra headers, modify request body unexpectedly & trigger an SSRF attack. When […]

Exploit Difficulty: HARD
⏱️ Time to exploit: > 4 hours
🛠️ Required skills: Advanced security expertise
💰 Public exploits: Rare or not public

How to Fix:

1 Identify affected systems

- Check if you're running the affected product

2 Immediate actions

- Update to the latest patched version
- If patching is not immediately possible: restrict network exposure, apply least-privilege access

3 Verification

- Test the fix in a staging environment first
- Review logs for signs of exploitation
- Monitor for IOCs (Indicators of Compromise)

4 Long-term prevention

- Enable automatic security updates
- Set up vulnerability monitoring
- Review and harden security configurations

Exploit Difficulty Assessment

HARD
⏱️ Time to Exploit: > 4 hours
🛠️ Skills Required: Advanced security expertise
💰 Public Exploits: Rare or not public

Vulnerability Timeline

Jan 01, 2026
Vulnerability Published

CVE details first published to NVD database

Jan 01, 2026
Imported to Database

Added to this CVE tracking system

Detection Rules & IOCs

No specific detection rules generated for this vulnerability type.

No vendor/product data available.