Is CVE-2023-42453 in the CISA KEV catalog?

No. CVE-2023-42453 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2023-42453?

CVE-2023-42453 has a CVSS v3 base score of 3.1 (LOW).

What is the EPSS score for CVE-2023-42453?

CVE-2023-42453 has an EPSS score of 0.65% (47th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2023-42453?

Upgrade matrix-synapse on debian unstable to 1.93.0-1 or later. Fixes are available for 2 affected products.

CVE & CISA-KEV Catalog

CVE-2023-42453

LOW

3.1

CVSS v3

NVD

Description

Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. Users were able to forge read receipts for any event (if they knew the room ID and event ID). Note that the users were not able to view the events, but simply mark it as read. This could be confusing as clients will show the event as read by the user, even if they are not in the room. This issue has been patched in version 1.93.0. Users are advised to upgrade. There are no known workarounds for this issue.

CWE-285

How to fix

Remediation Available

matrix-synapseDebian

Fixed in:1.93.0-1CVE-2023-42453

matrix-synapseUbuntu

Fixed in:0.24.0+dfsg-1ubuntu0.1~esm4USN-7444-1

Fixed in:1.11.0-1ubuntu0.1~esm2USN-7444-1

Fixed in:1.53.0-1ubuntu0.1~esm2USN-7444-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityLow

AvailabilityNone

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N

Exploit Intelligence

0.65%probability of exploitation in 30 days

47thpercentile

Moderate risk: more likely to be exploited than 47% of all known CVEs.

References

Patch1

github.com

Vendor Advisory1

github.com

Mailing List2

Other references2

Related Vulnerabilities

Other CWE-285 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2025-29927	Critical	9.1	100%	-	Fix
CVE-2021-28799	Critical	10.0	78%	KEV + Ransom	Fix
CVE-2023-32707	High	8.8	74%	-	Fix
CVE-2023-48241	High	7.5	73%	-	Fix
CVE-2023-22480	High	7.3	67%	-	Fix
CVE-2022-3229	Critical	9.8	66%	-	-

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.