# CVE-2026-1801: Libsoup: libsoup: http request smuggling via malformed chunk headers

> Remote attackers can exploit HTTP request smuggling in libsoup via malformed chunk headers to potentially disclose sensitive information.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/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:** Yes
- **Published:** 3 Feb 2026
- **Updated:** 26 Mar 2026
- **Also known as:** AZL-76700, AZL-76736, DEBIAN-CVE-2026-1801, ECHO-47e4-5b68-7dd8, GHSA-xv49-34rf-rqv4, SUSE-SU-2026:22061-1, SUSE-SU-2026:22071-1, SUSE-SU-2026:2654-1, SUSE-SU-2026:2670-1, SUSE-SU-2026:2702-1, UBUNTU-CVE-2026-1801, openSUSE-SU-2026:10917-1, openSUSE-SU-2026:20895-1

## What is CVE-2026-1801?

CVE-2026-1801 is a medium-severity vulnerability in Redhat Enterprise Linux, published on 3 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A flaw was found in libsoup, an HTTP client/server library. This HTTP Request Smuggling vulnerability arises from non-RFC-compliant parsing in the soup_filter_input_stream_read_line() logic, where libsoup accepts malformed chunk headers, such as lone line feed (LF) characters instead of the required carriage return and line feed (CRLF). A remote attacker can exploit this without authentication or user interaction by sending specially crafted chunked requests. This allows libsoup to parse and process multiple HTTP requests from a single network message, potentially leading to information disclosure.

Weakness: CWE-444 (Inconsistent Interpretation of HTTP Requests)

## Which versions are affected by CVE-2026-1801?

It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `libsoup2` | SUSE:Linux Enterprise Micro 5.3 | All versions | 2.74.2-150400.3.37.1 |
| `libsoup2` | SUSE:Linux Enterprise Micro 5.4 | All versions | 2.74.2-150400.3.37.1 |
| `libsoup2` | SUSE:Linux Enterprise Micro 5.5 | All versions | 2.74.2-150400.3.37.1 |
| `libsoup2` | SUSE:Linux Enterprise Module for Basesystem 15 SP7 | All versions | 2.74.3-150600.4.36.1 |
| `libsoup` | SUSE:Linux Enterprise Server LTSS Extended Security 12 SP5 | All versions | 2.62.2-5.43.1 |
| `libsoup` | SUSE:Linux Micro 6.0 | All versions | 3.4.2-16.1 |
| `libsoup` | SUSE:Linux Micro 6.1 | All versions | 3.4.4-slfo.1.1_10.1 |
| `libsoup2` | openSUSE:Tumbleweed | All versions | 2.74.3-21.1 |

Products: Gnome Libsoup, Redhat Enterprise Linux.

## How do I fix CVE-2026-1801?

Apply the vendor's patch.

## Is CVE-2026-1801 being exploited?

There is no known exploitation of CVE-2026-1801 in the wild and no public exploit code.

Public exploit code:

- https://github.com/misterdengi/CVE-2026-1801C (github_poc): https://github.com/misterdengi/CVE-2026-1801C

## 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-2026-1801 and fix it if it is affected.

What it is: CVE-2026-1801 is a medium-severity vulnerability in Redhat Enterprise Linux, published on 3 Feb 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-2026-1801 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-2026-1801/ (Markdown: https://insights.sbomify.com/CVE-2026-1801/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-1801
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-1801
- OSV: https://osv.dev/vulnerability/CVE-2026-1801

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-1801/
Summaries are generated and may contain mistakes; the official description above is the record.