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.
CVE-2024-37302
This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.6%, top 56% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- High severity, but no confirmed exploitation yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 7.5
- EG Score
- 7.5(medium)
- EG Risk
- 49(Track)EG Risk 49/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity75% × 45%Exploitation1% × 40%Automatability100% × 15%Action: Routine — remediate on your standard cadence. - EPSS
- 43.8%
- KEV
- Not listed
Published
December 3, 2024
Last Modified
August 26, 2025
References (1)
- security-advisories@githubhttps://github.com/element-hq/synapse/security/advisories/GHSA-4mhg-xv73-xq2x
Vendor Advisories for CVE-2024-37302(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(1 across 1 ecosystem)
PyPI(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| matrix-synapse | 0.33.5 ... 1.99.0rc1 (378 versions) | 1.106.0 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 12× in last 7d / 47× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-23 02:38 UTCEG score recompute
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Related CVEs(same CWE)
Same CWE
10 shownCWE-770
- CVE-2018-20033EG 9.8CRITICAL
- CVE-2019-11479NVD 7.5EG 9.0EPSS 100%HIGH
- CVE-2019-11478NVD 5.3EG 9.0EPSS 100%MEDIUM
- CVE-2019-10088EG 8.8EPSS 91%HIGH
- CVE-2018-15462EG 8.6HIGH
- CVE-2018-15460EG 8.6HIGH
- CVE-2018-0137EG 8.6HIGH
- CVE-2008-5180NVD 5.3EG 7.9EPSS 99%MEDIUM
- CVE-2019-10094EG 7.8HIGH
- CVE-2018-16865EG 7.8HIGH
Frequently asked(5)
What is CVE-2024-37302?
When was CVE-2024-37302 disclosed?
Is CVE-2024-37302 actively exploited?
What is the CVSS score of CVE-2024-37302?
How do I remediate CVE-2024-37302?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2024-37302
Is Your Infrastructure Affected by CVE-2024-37302?
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