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CVE-2018-10657

Matrix Synapse DoS

7.5 HighFix available

CVE-2018-10657 is a high vulnerability (CVSS 7.5) in Matrix Synapse, published May 2, 2018. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.49%, the 74th percentile. Fixed in matrix-synapse 0.28.1.

Matrix Synapse before 0.28.1 is prone to a denial of service flaw where malicious events injected with depth = 2^63 - 1 render rooms unusable, related to federation/federation_base.py and handlers/message.py, as exploited in the wild in April 2018.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

1.49%Up 0.7 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 7.5

Matrix Synapse before 0.28.1 is prone to a denial of service flaw where malicious events injected with depth = 2^63 - 1 render rooms unusable, related to federation/federation_base.py and handlers/message.py, as exploited in the wild in April 2018.

Record
CVE-2018-10657
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0
5.0 MediumAV:N/AC:L/Au:N/C:N/I:N/A:P
Weakness
CWE-20
Updated
2026-11-02
CVE List No score

Matrix Synapse before 0.28.1 is prone to a denial of service flaw where malicious events injected with depth = 2^63 - 1 render rooms unusable, related to federation/federation_base.py and handlers/message.py, as exploited in the wild in April 2018.

Record
CVE-2018-10657
Updated
2026-11-02
EUVDEUVD-2022-5380 No score

Matrix Synapse before 0.28.1 is prone to a denial of service flaw where malicious events injected with depth = 2^63 - 1 render rooms unusable, related to federation/federation_base.py and handlers/message.py, as exploited in the wild in April 2018.

Record
EUVD-2022-5380
Updated
2026-11-03
GitHub AdvisoriesGHSA-vmcc-4p4x-x7wg 7.5

Matrix Synapse DoS

Matrix Synapse before 0.28.1 is prone to a denial of service flaw where malicious events injected with depth = 2<sup>63</sup> - 1 render rooms unusable, related to federation/federation_base.py and handlers/message.py, as exploited in the wild in April 2018.

Record
GHSA-vmcc-4p4x-x7wg
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-20
Updated
2026-11-02
OSV 7.5

Matrix Synapse before 0.28.1 is prone to a denial of service flaw where malicious events injected with depth = 2^63 - 1 render rooms unusable, related to federation/federation_base.py and handlers/message.py, as exploited in the wild in April 2018.

Record
CVE-2018-10657
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVDEBIAN-CVE-2018-10657 7.5

Matrix Synapse before 0.28.1 is prone to a denial of service flaw where malicious events injected with depth = 2^63 - 1 render rooms unusable, related to federation/federation_base.py and handlers/message.py, as exploited in the wild in April 2018.

Record
DEBIAN-CVE-2018-10657
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
Show 4 moreShow less
OSVGHSA-vmcc-4p4x-x7wg 7.5

Matrix Synapse DoS

Matrix Synapse before 0.28.1 is prone to a denial of service flaw where malicious events injected with depth = 2<sup>63</sup> - 1 render rooms unusable, related to federation/federation_base.py and handlers/message.py, as exploited in the wild in April 2018.

Record
GHSA-vmcc-4p4x-x7wg
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-20
Updated
2026-11-02
OSVPYSEC-2026-846 7.5

Matrix Synapse DoS

Matrix Synapse before 0.28.1 is prone to a denial of service flaw where malicious events injected with depth = 2<sup>63</sup> - 1 render rooms unusable, related to federation/federation_base.py and handlers/message.py, as exploited in the wild in April 2018.

Record
PYSEC-2026-846
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2018-10657 7.5

Matrix Synapse before 0.28.1 is prone to a denial of service flaw where malicious events injected with depth = 2^63 - 1 render rooms unusable, related to federation/federation_base.py and handlers/message.py, as exploited in the wild in April 2018.

Record
UBUNTU-CVE-2018-10657
CVSS 3.0
7.5 HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVUSN-6076-1 No score

matrix-synapse vulnerabilities

It was discovered that Synapse incorrectly handled certain inputs. If a user or an automated system were tricked into opening a specially crafted input file, a remote attacker could possibly use this issue to cause a denial of service. (CVE-2019-18835, CVE-2018-12291, CVE-2018-10657)

It was discovered that Synapse incorrectly handled certain inputs. If a user or an automated system were tricked into opening a specially crafted input file, a remote attacker could possibly use this issue to hijack the session. (CVE-2019-11842, CVE-2018-12423)

It was discovered that Synapse incorrectly handled certain inputs. If a user or an automated system were tricked into opening a specially crafted input file, a remote attacker could possibly use this issue to perform spoofing or user impersonation. (CVE-2019-5885, CVE-2018-16515)

Record
USN-6076-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
matrix-synapse
PyPI
 before 0.28.1
0.28.1
matrix-synapse
Ubuntu:Pro:18.04:LTS
 before 0.24.0+dfsg-1ubuntu0.1~esm1, plus listed versions
0.19.2+dfsg-60.24.0+dfsg-1
0.24.0+dfsg-1ubuntu0.1~esm1

History

History
WhenChangedSources
2026-11-03affected
2026-11-03aliasesEUVD
2026-11-02createdCVE List, GitHub Advisories, NVD, OSV

References

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