How severe is CVE-2024-37302?

CVE-2024-37302 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2024-37302?

CVE-2024-37302 affects the following packages: matrix-synapse (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2024-37302?

Update matrix-synapse to 1.106 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-37302 is resolved across your whole dependency graph.

How do I detect CVE-2024-37302 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for matrix-synapse. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2024-37302 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2024-37302?

O3 pinpoints whether CVE-2024-37302 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2024-37302 actively exploited in the wild?

No public exploit code has been indexed for CVE-2024-37302 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2024-37302?

CVE-2024-37302 has an EPSS (Exploit Prediction Scoring System) score of 0.6%, placing it in the 42th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

When was CVE-2024-37302 published, and has it been updated?

CVE-2024-37302 was published on December 3, 2024 and was last updated on May 20, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2024-37302: matrix-synapse Denial of Service (High 7.5)

EPSS Exploitation Probability

via FIRST.org ↗

0.6%probability of exploitation in next 30 days

Lower Risk42th percentile-0.01%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

🐍matrix-synapse

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`matrix-synapse`	all versions	1.106

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for matrix-synapse. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update matrix-synapse to 1.106 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-37302 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2024-37302 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2024-37302. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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

O3 Security · Impact-Aware SCA

Is CVE-2024-37302 in your dependencies?

O3 detects CVE-2024-37302 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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CVE-2024-37302