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

> Attackers can inject control characters into HTTP headers to manipulate CGI environment variables, potentially leading to code execution in TinyWeb.

- **Severity:** Critical 9.2 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 6 Mar 2026
- **Updated:** 6 Mar 2026
- **Also known as:** GHSA-r3gf-pg2c-m7mc

## What is CVE-2026-29046?

CVE-2026-29046 is a critical code injection vulnerability in maximmasiutin TinyWeb, published on 6 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-93 (Improper Neutralization of CRLF Sequences), CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component), CWE-20 (Improper Input Validation), CWE-114 (Process Control)

## Which versions are affected by CVE-2026-29046?

It affects 1 product.


Products: Ritlabs Tinyweb.

## How do I fix CVE-2026-29046?

No fix has been published for CVE-2026-29046 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-29046 being exploited?

There is no known exploitation of CVE-2026-29046 in the wild and no public exploit code.

## Other vulnerabilities in maximmasiutin TinyWeb

- [CVE-2026-27613](https://insights.sbomify.com/CVE-2026-27613/): CGI Parameter Injection (Bypass of STRICT_CGI_PARAMS and EscapeShellParam) (critical 10.0)
- [CVE-2026-22781](https://insights.sbomify.com/CVE-2026-22781/): TinyWeb CGI Command Injection (critical 10.0)
- [CVE-2026-28497](https://insights.sbomify.com/CVE-2026-28497/): TinyWeb: Integer Overflow in `_Val` (HTTP Request Smuggling) (critical 9.3)
- [CVE-2026-27630](https://insights.sbomify.com/CVE-2026-27630/): TinyWeb vulnerable to Remote Denial of Service via Thread/Connection Exhaustion (Slowloris) (high 8.7)
- [CVE-2026-27633](https://insights.sbomify.com/CVE-2026-27633/): TinyWeb has Unbounded Content-Length Memory Exhaustion (DoS) (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-29046 and fix it if it is affected.

What it is: CVE-2026-29046 is a critical code injection vulnerability in maximmasiutin TinyWeb, published on 6 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-29046 in the wild and no public exploit code.

Affected product: maximmasiutin TinyWeb. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-29046/ (Markdown: https://insights.sbomify.com/CVE-2026-29046/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-29046
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-29046
- OSV: https://osv.dev/vulnerability/CVE-2026-29046

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-29046/
Summaries are generated and may contain mistakes; the official description above is the record.