7.5

CVE-2025-30355: element-hq synapse Improper Input Validation

CVSS: 7.5v3.1HighAnalyzed
AliasesGHSA-v56r-hwv5-mxg6PYSEC-2026-1614UBUNTU-CVE-2025-30355
Published 27-03-2025Last modified 27-03-2025
Open JSON

Vulnerability summary

CVE-2025-30355 is a high (CVSS 7.5) Improper Input Validation vulnerability in element-hq synapse. EPSS estimates a 1.20% chance of exploitation in the next 30 days, higher than 67.7% of scored vulnerabilities.

Overall risk
30/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (NVD)
EPSS score
1.20%
0%100%
Low · +0.02 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 27-03-2025
    PublishedVulnerability first disclosed.
  2. 27-03-2025
    Last modifiedVulnerability information updated.

Description

Synapse is an open source Matrix homeserver implementation. A malicious server can craft events which, when received, prevent Synapse version up to 1.127.0 from federating with other servers. The vulnerability has been exploited in the wild and has been fixed in Synapse v1.127.1. No known workarounds are available.

CVSS metrics

5 scores · 5 sources · 1 version

EPSS trend

Probability

1.20%

Chance of exploitation in the next 30 days

Percentile

68%

Versus all other CVEs

30-day change

+0.02 pp

From 1.18% on 18-09-2026

18-09-202618-10-2026
EPSS score
1.20%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Debian1 product
  • matrix-synapse< 1.121.0-6
Element-hq1 product
Matrix1 product
Opensuse1 product
  • matrix-synapse&distro=openSUSE Tumbleweed< 1.127.1-1.1
PyPI1 product
  • matrix-synapse< 1.127.1
Ubuntu1 product
  • matrix-synapseAll versions (No fix recorded)

6 vendors · 6 products

References

12 links
Show all 12 references