Resource exhaustion in Element-Hq Synapse
CVE-2024-31208
Synapse is an open-source Matrix homeserver. A remote Matrix user with malicious intent, sharing a room with Synapse instances before 1.105.1, can dispatch specially crafted events to exploit a weakness in the V2 state resolution algorithm. This can induce high CPU consumption and accumulate excessive data in the database of such instances, resulting in a denial of service. Servers in private federations, or those that do not federate, are not affected. Server administrators should upgrade to 1.105.1 or later. Some workarounds are available. One can ban the malicious users or ACL block servers from the rooms and/or leave the room and purge the room using the admin API.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.015 (72.6th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 73rd percentile — 72.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.015 · newest: 0.015 · change: 0.000
Affected products
- Element-Hq Synapse — versions < 1.105.1
- Matrix Synapse
- Fedoraproject Fedora — versions 38, 39, 40
Weakness classification (CWE)
Public proof-of-concept exploits
References
- github.com/element-hq/synapse/security/advisories/GHSA-3h7q-rfh9-xm4v (Vendor Advisory)
- github.com/element-hq/synapse/commit/55b0aa847a61774b6a3acdc4b177a20dc019f01a (Patch)
- github.com/element-hq/synapse/releases/tag/v1.105.1 (Release Notes)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (Mailing List, Third Party Advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (Mailing List, Third Party Advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (Mailing List, Third Party Advisory)
Frequently asked questions
- What is CVE-2024-31208?
- CVE-2024-31208 is a medium-severity vulnerability in Element-Hq Synapse, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 6.5/10. Published 2024-04-23.
- How severe is CVE-2024-31208?
- Medium severity. CVSS v3 base score is 6.5 out of 10.
- Is CVE-2024-31208 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.