# GHSA-7h5v-85w9-pq6c: Denial of service (via resource exhaustion) due to improper input validation in third-party identifier endpoint

> Attackers can cause denial of service via resource exhaustion by sending unvalidated input to third-party identifier endpoints in Synapse.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 May 2021

## What is GHSA-7h5v-85w9-pq6c?

GHSA-7h5v-85w9-pq6c is a denial of service vulnerability in matrix-synapse, published on 19 May 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

### Impact
Missing input validation of some parameters on the endpoints used to confirm third-party identifiers could cause excessive use of disk space and memory leading to resource exhaustion.

### Patches
The issue is fixed by https://github.com/matrix-org/synapse/pull/9855.

### Workarounds
There are no known workarounds.

### References
n/a

### For more information
If you have any questions or comments about this advisory, email us at security@matrix.org.

## Which versions are affected by GHSA-7h5v-85w9-pq6c?

2 open source packages ship an affected version, including matrix-synapse.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `matrix-synapse` | PyPI | All versions | 1.33.0 |
| `matrix-synapse` | PyPI | All versions | 1.33.0 |

## How do I fix GHSA-7h5v-85w9-pq6c?

Upgrade matrix-synapse to 1.33.0 or later.

## Is GHSA-7h5v-85w9-pq6c being exploited?

There is no known exploitation of GHSA-7h5v-85w9-pq6c in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-7h5v-85w9-pq6c and fix it if it is affected.

What it is: GHSA-7h5v-85w9-pq6c is a denial of service vulnerability in matrix-synapse, published on 19 May 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of GHSA-7h5v-85w9-pq6c in the wild and no public exploit code.

Affected packages and fixed versions:
- matrix-synapse (PyPI): affected all versions; fixed in 1.33.0
- matrix-synapse (PyPI): affected all versions; fixed in 1.33.0

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/GHSA-7h5v-85w9-pq6c/ (Markdown: https://insights.sbomify.com/GHSA-7h5v-85w9-pq6c/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-7h5v-85w9-pq6c

---
From sbomify Insights: https://insights.sbomify.com/GHSA-7h5v-85w9-pq6c/
Summaries are generated and may contain mistakes; the official description above is the record.