# CVE-2026-48804: python-socketio: Binary attachment accumulation can cause denial of service

> An attacker can cause a denial of service by sending binary messages with missing attachments, forcing the server to retain them in memory indefinitely.

- **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:** 11 Aug 2026
- **Updated:** 13 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-48804, GHSA-5w7q-77mv-v69f, PYSEC-2026-3042, ROOT-APP-PYPI-CVE-2026-48804, SUSE-SU-2026:3086-1, UBUNTU-CVE-2026-48804, openSUSE-SU-2026:11171-1

## What is CVE-2026-48804?

CVE-2026-48804 is a high-severity denial of service vulnerability in miguelgrinberg python-socketio, published on 11 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

python-socketio is a Python implementation of the Socket.IO realtime client and server. The python-socketio server stores binary `EVENT` and `ACK` messages in memory while it waits to receive their binary attachments. Once all the attachments are received, these messages are then processed. Prior to version 5.16.4, an attacker can submit a binary message and intentionally omit sending one or more of its attachments to cause the message along with the partial list of received attachments to stay in memory for a long time. Version 5.16.4 takes the following measures to address this issue: Binary packets are only accepted from authenticated clients and, when a client disconnects, the server checks if there is a partial binary message being held for the client and deletes it.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2026-48804?

3 open source packages ship an affected version, including python-socketio.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `python-socketio` | PyPI | All versions | 5.16.2 |
| `python-socketio` | PyPI | All versions | 5.16.2 |
| `python-socketio` | PyPI | All versions | 5.16.2 |
| `python-python-socketio` | SUSE:Linux Enterprise Module for Python 3 15 SP7 | All versions | 5.7.2-150600.3.6.1 |
| `python-python-socketio` | SUSE:Linux Enterprise Server 15 SP6-LTSS | All versions | 5.7.2-150600.3.6.1 |
| `python-python-socketio` | SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | All versions | 5.7.2-150600.3.6.1 |
| `python-python-socketio` | openSUSE:Tumbleweed | All versions | 5.16.3-1.1 |

## How do I fix CVE-2026-48804?

Upgrade python-socketio to 5.16.2 or later.

## Is CVE-2026-48804 being exploited?

There is no known exploitation of CVE-2026-48804 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-48804 and fix it if it is affected.

What it is: CVE-2026-48804 is a high-severity denial of service vulnerability in miguelgrinberg python-socketio, published on 11 Aug 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-2026-48804 in the wild and no public exploit code.

Affected packages and fixed versions:
- python-socketio (PyPI): affected all versions; fixed in 5.16.2
- python-socketio (PyPI): affected all versions; fixed in 5.16.2
- python-socketio (PyPI): affected all versions; fixed in 5.16.2

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-2026-48804/ (Markdown: https://insights.sbomify.com/CVE-2026-48804/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-48804
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-48804
- OSV: https://osv.dev/vulnerability/CVE-2026-48804

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-48804/
Summaries are generated and may contain mistakes; the official description above is the record.