# CVE-2026-15709: Denial of service in Red Hat Enterprise Linux 10

> Remote attackers can cause denial of service in applications using libsoup by sending compressed WebSocket payloads that trigger unbounded memory allocation.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Jul 2026
- **Updated:** 24 Sep 2026
- **Also known as:** AZL-92411, DEBIAN-CVE-2026-15709, ECHO-3953-b7bd-49be, GHSA-gv2g-7h3v-q5f3, ROOT-OS-DEBIAN-12-CVE-2026-15709, ROOT-OS-DEBIAN-13-CVE-2026-15709, UBUNTU-CVE-2026-15709

## What is CVE-2026-15709?

CVE-2026-15709 is a high-severity denial of service vulnerability in Red Hat Enterprise Linux 10, published on 14 Jul 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's WebSocket implementation when using the permessage-deflate extension. The extension's decompression loop (inflate()) processes data in chunks without enforcing an upper boundary limit on the output buffer size. While libsoup limits the incoming compressed frame size via max_incoming_payload_size, it fails to track or limit memory allocation during decompression. A separate check for decompressed size (max_total_message_size) exists but executes only after inflation is complete, and it is entirely disabled by default for client connections. A remote, unauthenticated attacker can exploit this by sending a small, highly compressed payload (a decompression bomb), causing unbounded memory allocation that triggers an Out-of-Memory (OOM) crash and a Denial of Service (DoS).

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

## Which versions are affected by CVE-2026-15709?


## How do I fix CVE-2026-15709?

Apply the vendor's patch.

## Is CVE-2026-15709 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-15709 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-15709 and fix it if it is affected.

What it is: CVE-2026-15709 is a high-severity denial of service vulnerability in Red Hat Enterprise Linux 10, published on 14 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-15709 exists.

Affected product: Red Hat Enterprise Linux 10. 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-2026-15709/ (Markdown: https://insights.sbomify.com/CVE-2026-15709/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-15709
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-15709
- OSV: https://osv.dev/vulnerability/CVE-2026-15709

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-15709/
Summaries are generated and may contain mistakes; the official description above is the record.