Is CVE-2021-34813 in the CISA KEV catalog?

No. CVE-2021-34813 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-34813?

CVE-2021-34813 has a CVSS v3 base score of 9.8 (CRITICAL).

What is the EPSS score for CVE-2021-34813?

CVE-2021-34813 has an EPSS score of 4.26% (90th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-34813?

Upgrade olm on debian 12 to 3.2.3~dfsg-3 or later. Fixes are available for 3 affected products.

CVE & CISA-KEV Catalog

CVE-2021-34813

CRITICALEPSS 90th pctl

9.8

CVSS v3

NVD

Description

Matrix libolm before 3.2.3 allows a malicious Matrix homeserver to crash a client (while it is attempting to retrieve an Olm encrypted room key backup from the homeserver) because olm_pk_decrypt has a stack-based buffer overflow. Remote code execution might be possible for some nonstandard build configurations.

CWE-787Out-of-bounds Write

How to fix

Remediation Available

olmDebian

Fixed in:3.2.3~dfsg-3CVE-2021-34813

libolm3Ubuntu

Fixed in:3.1.3+dfsg-2ubuntu0.1~esm1USN-5194-1

olmUbuntu

Fixed in:3.1.3+dfsg-2ubuntu0.1~esm1USN-5194-1

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 ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

4.26%probability of exploitation in 30 days

90thpercentile

Elevated risk: more likely to be exploited than 90% of all known CVEs.

References

Patch2

Vendor Advisory1

gitlab.matrix.org

Related Vulnerabilities

Other CWE-787 (Out-of-bounds Write) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2025-22457	Critical	9.0	100%	KEV + Ransom	Fix
CVE-2025-0282	Critical	9.0	100%	KEV + Ransom	-
CVE-2015-3113	Critical	9.8	100%	KEV	Fix
CVE-2021-20038	Critical	9.8	100%	KEV + Ransom	-
CVE-2023-4863	High	8.8	100%	KEV	Fix
CVE-2020-16040	Medium	6.5	100%	-	Fix

Embed a live status badge for CVE-2021-34813

Markdown

[![CVE-2021-34813](https://tridentstack.com/cve/badge/CVE-2021-34813.svg)](https://tridentstack.com/cve/CVE-2021-34813)

HTML

<a href="https://tridentstack.com/cve/CVE-2021-34813"><img src="https://tridentstack.com/cve/badge/CVE-2021-34813.svg" alt="CVE-2021-34813"></a>

Find and fix vulnerabilities across your fleet

TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.

Start free

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.