CVE-2024-37302 | Synapse denial of service through media disk space consumption

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.

Published: 2024-12-03 Last update: 2025-08-26 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2024-37302 is rated Moderate Risk (53.9/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.57%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2024-37302

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-23 0.74% 0.57% -0.17%
2 2026-05-17 0.48% 0.74% +0.26%
3 2026-01-11 — 0.48% —

Full EPSS history (18 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2024-37302

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2024-37302

GitHub Security Advisory for CVE-2024-37302

GHSA-4mhg-xv73-xq2x · Severity: high · Ecosystem: pip — Synapse denial of service through media disk space consumption

OS Trackers for CVE-2024-37302

vendor priority summary link
alpine — CVE-2024-37302: 1 source package rows (synapse); 36 state rows across 4 repos (3.20-community, 3.21-community, 3.22-community, edge-community); fixed 4, open 32. https://security.alpinelinux.org/vuln/CVE-2024-37302
debian not yet assigned CVE-2024-37302 not yet assigned priority: Debian including 1 source packages (matrix-synapse), 2 status rows across 2 suites (forky, sid): resolved 2. https://security-tracker.debian.org/tracker/CVE-2024-37302
ubuntu medium CVE-2024-37302 medium priority: Ubuntu including 1 source packages (matrix-synapse), 6 status rows across 6 suites (bionic, focal, jammy, noble, oracular, upstream): deferred 4, ignored 1, released 1. https://ubuntu.com/security/CVE-2024-37302

Affected software / configurations for CVE-2024-37302

Vendor Product Version Raw CPE
matrix synapse < 1.106.0 cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:*

References for CVE-2024-37302

cvelogic Threat Intelligence