# CVE-2026-103930: cpp-httplib open_stream serializes CRLF in request target into HTTP request line

> Attacker can inject CRLF bytes into HTTP request lines via open_stream, modifying backend-visible request data in cpp-httplib.

- **Severity:** Low 3.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Oct 2026
- **Updated:** 15 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-103930, GHSA-vq69-f637-8fhr, UBUNTU-CVE-2026-103930

## What is CVE-2026-103930?

CVE-2026-103930 is a low-severity vulnerability in yhirose cpp-httplib, published on 14 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

cpp-httplib is a C++ header-only HTTP/HTTPS library. From 0.29.0 until 0.51.0, Client::open_stream in httplib.h accepts a caller-controlled path that reaches detail::write_request_line() without the detail::encode_path() protection used by the ordinary buffered request path. Raw carriage-return and line-feed bytes in the path can therefore split the outbound HTTP/1.1 request line and inject attacker-shaped request metadata. Exploitation requires an embedding application to pass remote user input into the open_stream path and a backend or intermediary that interprets the injected bytes; the established impact is modification of backend-visible request data, not direct confidentiality or availability impact. This issue is fixed in version 0.51.0.

Weakness: CWE-113 (Improper Neutralization of CRLF Sequences in HTTP Headers)

## Which versions are affected by CVE-2026-103930?


## How do I fix CVE-2026-103930?

No fix has been published for CVE-2026-103930 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-103930 being exploited?

There is no known exploitation of CVE-2026-103930 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-103930 and fix it if it is affected.

What it is: CVE-2026-103930 is a low-severity vulnerability in yhirose cpp-httplib, published on 14 Oct 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-2026-103930 in the wild and no public exploit code.

Affected product: yhirose cpp-httplib. 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-2026-103930/ (Markdown: https://insights.sbomify.com/CVE-2026-103930/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-103930
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-103930
- OSV: https://osv.dev/vulnerability/CVE-2026-103930

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-103930/
Summaries are generated and may contain mistakes; the official description above is the record.