CVE-2024-37302 Synapse denial of service through media disk space consumption
Unauthenticated attackers can exhaust disk space by triggering excessive remote media downloads, causing denial of service in Synapse Matrix homeservers.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-37302?
CVE-2024-37302 is a high-severity denial of service vulnerability in element-hq synapse, published on 3 Dec 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Synapse is an open-source Matrix homeserver. Synapse versions before 1.106 are vulnerable to a disk fill attack, where an unauthenticated adversary can induce Synapse to download and cache large amounts of remote media. The default rate limit strategy is insufficient to mitigate this. This can lead to a denial of service, ranging from further media uploads/downloads failing to completely unavailability of the Synapse process, depending on how Synapse was deployed. Synapse 1.106 introduces a new "leaky bucket" rate limit on remote media downloads to reduce the amount of data a user can request at a time. This does not fully address the issue, but does limit an unauthenticated user's ability to request large amounts of data to be cached.
Weakness: CWE-770
Which versions are affected by CVE-2024-37302?
3 open source packages ship an affected version, including matrix-synapse. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
matrix-synapse PyPI | All versions | 1.106 |
matrix-synapse PyPI | All versions | 1.106 |
matrix-synapse PyPI | All versions | 1.106.0 |
Products include Matrix Synapse.
How do I fix CVE-2024-37302?
Upgrade matrix-synapse to a fixed version for your release line: 1.106 or 1.106.0.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2024-37302 being exploited?
There is no known exploitation of CVE-2024-37302 in the wild and no public exploit code.
Other vulnerabilities in element-hq synapse
- CVE-2019-18835 Improper Verification of Cryptographic Signature in matrix-synapse
- CVE-2024-52815 Synapse allows a a malformed invite to break the invitee's `/sync`
- CVE-2024-52805 Synapse allows unsupported content types to lead to memory exhaustion
- CVE-2024-53863 Synapse can be forced to thumbnail unexpected file formats, invoking external, potentially untrustworthy decoders
- CVE-2018-12423 Matrix Synapse Authorization Error
Sources
Also known as GHSA-4mhg-xv73-xq2x, PYSEC-2024-286, UBUNTU-CVE-2024-37302.