CVE-2021-213945.3MediumCWE-20

CVE-2021-21394: Denial of service (via resource exhaustion) due to improper input validation on third-party identifier endpoints

matrix-org · synapse

Fixed in 1.28.0 · Affected: matrix-org synapse before 1.28.0 · Exploitation: possible (1 to 10%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

1.5%probability of exploitation in the next 30 days

75th percentile

050100

Higher than 75% of scored CVEs

5.3MediumCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP. In Synapse before version 1.28.0 Synapse is missing input validation of some parameters on the endpoints used to confirm third-party identifiers could cause excessive use of disk space and memory leading to resource exhaustion. Note that the groups feature is not part of the Matrix specification and the chosen maximum lengths are arbitrary. Not all clients might abide by them. Refer to referenced GitHub security advisory for additional details including workarounds.

Affected products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

matrix-org · synapse< 1.28.0

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Possible (1 to 10%). EPSS between 1% and 10%.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Improper Input Validation · Input Validation and Logic
Vendor: matrix-org
Published: April 2021
Band: Possible (1 to 10%), April 2021

CoverageNo articles yet

No CyberSIXT article names CVE-2021-21394 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.