Is CVE-2021-40823 in the CISA KEV catalog?

No. CVE-2021-40823 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-40823?

CVE-2021-40823 has a CVSS v3 base score of 5.9 (MEDIUM).

What is the EPSS score for CVE-2021-40823?

CVE-2021-40823 has an EPSS score of 0.64% (46th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-40823?

Upgrade javascript sdk to 12.4.1 or later.

CVE & CISA-KEV Catalog

CVE-2021-40823

MEDIUM

5.9

CVSS v3

NVD

Description

A logic error in the room key sharing functionality of matrix-js-sdk (aka Matrix Javascript SDK) before 12.4.1 allows a malicious Matrix homeserver present in an encrypted room to steal room encryption keys (via crafted Matrix protocol messages) that were originally sent by affected Matrix clients participating in that room. This allows the homeserver to decrypt end-to-end encrypted messages sent by affected clients.

CWE-290

How to fix

Remediation Available

javascript sdkNVD

Affected:< 12.4.1Fixed in:12.4.1CVE-2021-40823derived from NVD

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 RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityNone

AvailabilityNone

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

Exploit Intelligence

0.64%probability of exploitation in 30 days

46thpercentile

Moderate risk: more likely to be exploited than 46% of all known CVEs.

References

Vendor Advisory1

matrix.org

Third-Party Advisory1

github.com

Related Vulnerabilities

Other CWE-290 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-4358	Critical	9.8	97%	KEV	-
CVE-2022-24112	Critical	9.8	96%	KEV	Fix
CVE-2022-23131	Critical	9.1	96%	KEV	-
CVE-2021-29441	High	8.6	74%	-	Fix
CVE-2021-31195	Medium	6.5	74%	-	Fix
CVE-2020-7388	Critical	10.0	70%	-	Fix

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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.