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CVE-2023-45129

17
FAUCET Score

CVE-2023-45129 is a denial-of-service vulnerability affecting Synapse, an open-source Matrix homeserver, prior to version 1.94.0. A malicious server ACL event can temporarily or permanently degrade performance, leading to a persistent denial of service for affected homeservers. The vulnerability has a CVSS score of 4.9 (MEDIUM), indicating a high impact on availability with low attack complexity, and affects products like fedoraproject fedora and matrix synapse. There is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 1.94.0CPE matchmatch criteria
cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:*
37CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:37:*:*:*:*:*:*:*
38CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

4.9MEDIUM

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
HIGH
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
1.2
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.17%
Probability of exploitation in next 30 days
EPSS Percentile
64.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0117 is in the 71st percentile among its peer group of 3,565 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
pippatch availablevia ghsa
Product: matrix-synapseFixed in: 1.94.0

Vendor Advisories (2)

pipGHSA-5chr-wjw5-3gq4medium

matrix-synapse vulnerable to denial of service due to malicious server ACL events

Oct 10, 2023
redhatCVE-2023-45129Moderate

synapse: malicious ACL event can cause denial of service

Oct 10, 2023

References

github.com / matrix-org/synapse/pull/16360
PatchVendor Advisory
github.com / matrix-org/synapse/security/advisories/GHSA-5chr-wjw5-3gq4
Vendor Advisory
lists.fedoraproject.org / archives/list/[email protected]/message/KEVRB4MG5UXQ5RLZHSUJXM5GWEBYYS5B
Mailing List
lists.fedoraproject.org / archives/list/[email protected]/message/N6P4QULVUE254WI7XF2LWWOGHCYVFXFY
lists.fedoraproject.org / archives/list/[email protected]/message/WRO4MPQ6HOXIUZM6RJP6VTCTMV7RD2T3
Mailing List
matrix-org.github.io / synapse/latest/admin_api/rooms.html
Release Notes
security.gentoo.org / glsa/202401-12