Is CVE-2023-38691 in the CISA KEV catalog?

No. CVE-2023-38691 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2023-38691?

CVE-2023-38691 has a CVSS v3 base score of 5.0 (MEDIUM).

What is the EPSS score for CVE-2023-38691?

CVE-2023-38691 has an EPSS score of 0.39% (31th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2023-38691?

Upgrade matrix-appservice-bridge to 8.1.2 or later.

CVE & CISA-KEV Catalog

CVE-2023-38691

MEDIUM

5.0

CVSS v3

NVD

Description

matrix-appservice-bridge provides an API for setting up bridges. Starting in version 4.0.0 and prior to versions 8.1.2 and 9.0.1, a malicious Matrix server can use a foreign user's MXID in an OpenID exchange, allowing a bad actor to impersonate users when using the provisioning API. The library does not check that the servername part of the `sub` parameter (containing the user's *claimed* MXID) is the the same as the servername we are talking to. A malicious actor could spin up a server on any given domain, respond with a `sub` parameter according to the user they want to act as and use the resulting token to perform provisioning requests. Versions 8.1.2 and 9.0.1 contain a patch. As a workaround, disable the provisioning API.

CWE-287Improper Authentication

How to fix

Remediation Available

matrix-appservice-bridgeNVD

Affected:>= 4.0.0, < 8.1.2Fixed in:8.1.2CVE-2023-38691derived 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 ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeChanged

Impact

ConfidentialityLow

IntegrityNone

AvailabilityNone

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

Exploit Intelligence

0.39%probability of exploitation in 30 days

31stpercentile

Low risk: more likely to be exploited than 31% of all known CVEs.

References

Patch1

github.com

Third-Party Advisory1

github.com

Related Vulnerabilities

Other CWE-287 (Improper Authentication) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-35082	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2023-35078	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2017-7921	Critical	9.8	100%	KEV	-
CVE-2024-7593	Critical	9.8	100%	KEV	-
CVE-2023-46805	High	8.2	100%	KEV + Ransom	-
CVE-2022-40684	Critical	9.8	100%	KEV + Ransom	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.