# CVE-2026-53524: WeeChat has a Decompression Bomb in Relay WebSocket (DoS)

> An authenticated user can crash WeeChat by sending a small compressed WebSocket frame that decompresses to gigabytes, exhausting memory.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 21 Aug 2026
- **Updated:** 24 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-53524, GHSA-v2v4-45wm-5cr3, UBUNTU-CVE-2026-53524

## What is CVE-2026-53524?

CVE-2026-53524 is a medium-severity denial of service vulnerability in weechat, published on 21 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

WeeChat (Wee Enhanced Environment for Chat) is a free chat client. In versions 4.3.0 through 4.9.0, the WeeChat relay module's WebSocket permessage-deflate decompression function relay_websocket_inflate() has no upper bound on output size. An authenticated relay user can send a small compressed WebSocket frame (~100 bytes) that decompresses to gigabytes, exhausting all server memory and crashing the entire WeeChat process. The api protocol enables permessage-deflate and requires authentication before WebSocket upgrade. Version 4.9.1 patches the issue.

Weakness: CWE-409 (Improper Handling of Highly Compressed Data (Data Amplification))

## Which versions are affected by CVE-2026-53524?


## How do I fix CVE-2026-53524?

Upgrade to a fixed version.

## Is CVE-2026-53524 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53524 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53524 and fix it if it is affected.

What it is: CVE-2026-53524 is a medium-severity denial of service vulnerability in weechat, published on 21 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53524 exists.

Affected product: weechat. 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-2026-53524/ (Markdown: https://insights.sbomify.com/CVE-2026-53524/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53524
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53524
- OSV: https://osv.dev/vulnerability/CVE-2026-53524

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53524/
Summaries are generated and may contain mistakes; the official description above is the record.