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Fencer Vulns
low 2.7

CVE-2026-45076 json

Synapse pagination denial of service

published 2026-05-14 5 mo ago modified 2026-10-26 14 d ago also EUVD-2026-32934 , GHSA-6qf2-7x63-mm6v , PYSEC-2026-194

cvss
2.7
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 30%
public exploits
0
none known

Summary

Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, in federated rooms, malicious homeservers can craft room events in such a way that prevents Synapse from providing full history to paginating clients. Clients could therefore fail to display room history. This vulnerability is fixed in 1.152.1.

Patch / fix

  • pypi matrix-synapse 1.152.1
  • element-hq synapse 1.152.1
  • element synapse 1.152.1
  • matrix synapse 1.152.1
  • matrix-synapse openSUSE Tumbleweed 1.153.0-2.1

opensuse advisories openSUSE-SU-2026:10898-1

  • synapse Alpine 3.24, Alpine 3.23 1.152.1-r0

alpine advisories ALPINE-CVE-2026-45076

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-45076 updated cvss 2.7

Synapse: matrix-synapse: Synapse pagination denial of service

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 30% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 5.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
CNA 4.0 5.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 2.7 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L
OSV 3.1 2.7 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L

Affected packages

ecosystem package affected fixed in
pypi matrix-synapse
<1.152.1
1.152.1

Affected products

  • element-hq synapse

Classification

Weakness
  • CWE-20 Improper Input Validation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.