# CVE-2026-3632: Libsoup: libsoup: http smuggling and server-side request forgery via malformed hostnames

> Attackers can exploit hostname validation flaws in libsoup to perform HTTP smuggling and Server-Side Request Forgery, potentially accessing internal systems.

- **Severity:** Low 3.9 (`CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 17 Mar 2026
- **Updated:** 19 Mar 2026
- **Also known as:** AZL-80229, DEBIAN-CVE-2026-3632, ECHO-cd7e-c6ba-0346, GHSA-v5mp-vx4p-jwp6, UBUNTU-CVE-2026-3632

## What is CVE-2026-3632?

CVE-2026-3632 is a low-severity server-side request forgery vulnerability in Redhat Enterprise Linux, published on 17 Mar 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

### Official description

A flaw was found in libsoup, a library used by applications to send network requests. This vulnerability occurs because libsoup does not properly validate hostnames, allowing special characters to be injected into HTTP headers. A remote attacker could exploit this to perform HTTP smuggling, where they can send hidden, malicious requests alongside legitimate ones. In certain situations, this could lead to Server-Side Request Forgery (SSRF), enabling an attacker to force the server to make unauthorized requests to other internal or external systems. The impact is low, as SoupServer is not actually used in internet infrastructure.

Weakness: CWE-1286 (Improper Validation of Syntactic Correctness of Input)

## Which versions are affected by CVE-2026-3632?

It affects 2 products.


Products: Gnome Libsoup, Redhat Enterprise Linux.

## How do I fix CVE-2026-3632?

Apply the vendor's patch.

## Is CVE-2026-3632 being exploited?

There is no known exploitation of CVE-2026-3632 in the wild and no public exploit code.

## Other vulnerabilities in Redhat Enterprise Linux

- [CVE-2026-102556](https://insights.sbomify.com/CVE-2026-102556/): Libsoup: libsoup: heap buffer overflow from websocket pong signal type confusion (high 8.6)
- [CVE-2026-102557](https://insights.sbomify.com/CVE-2026-102557/): Libsoup: libsoup: heap buffer overflow during websocket message reassembly (high 8.6)
- [CVE-2026-102558](https://insights.sbomify.com/CVE-2026-102558/): Libsoup: libsoup: heap buffer overflow during websocket receive-buffer growth (high 8.6)
- [CVE-2026-102559](https://insights.sbomify.com/CVE-2026-102559/): Libsoup: libsoup: heap buffer overflow during websocket client-frame masking (high 8.6)
- [CVE-2026-102560](https://insights.sbomify.com/CVE-2026-102560/): Libsoup: libsoup: heap buffer overflow during outgoing permessage-deflate buffer growth (high 8.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-3632 and fix it if it is affected.

What it is: CVE-2026-3632 is a low-severity server-side request forgery vulnerability in Redhat Enterprise Linux, published on 17 Mar 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-3632 in the wild and no public exploit code.

Affected product: Redhat Enterprise Linux. 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-2026-3632/ (Markdown: https://insights.sbomify.com/CVE-2026-3632/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-3632
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-3632
- OSV: https://osv.dev/vulnerability/CVE-2026-3632

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-3632/
Summaries are generated and may contain mistakes; the official description above is the record.