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CVE-2018-12291

22
FAUCET Score

CVE-2018-12291 describes a security vulnerability in Matrix Synapse versions prior to 0.31.1, specifically within the on_get_missing_events function in handlers/federation.py. This flaw allows for the incorrect application of event visibility rules during the get_missing_events federation API call. With a CVSS score of 7.5 (HIGH), it represents a critical unauthenticated remote attack (AV:N/AC:L/PR:N/UI:N) that could lead to high confidentiality impact (C:H) by exposing sensitive event data. Despite its severity, there is no evidence of active exploitation, publicly available exploit code, or significant community discussion or media coverage surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
< 0.31.1CPE matchmatch criteria
cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

7.5HIGH

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.0

Exploit Intelligence

EPSS Score
1.80%
Probability of exploitation in next 30 days
EPSS Percentile
76.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0181 is in the 59th percentile among its peer group of 51,553 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 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: 0.31.1

Vendor Advisories (1)

pipGHSA-v8wm-g9f2-xjv4high

Matrix Synapse Security Filtering Flaw

May 13, 2022

References

github.com / matrix-org/synapse/pull/3371
PatchThird Party Advisory
github.com / matrix-org/synapse/releases/tag/v0.31.1
Third Party Advisory