Matrix
CVE-2021-34813
CRITICAL
Vulnerability Assessment
| Weakness |
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, write limits
MITRE ATT&CK
2 techniques across 2 tactics: Execution, Privilege Escalation The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Impact | CVSS score of 9.8 (CRITICAL). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required. Public proof-of-concept exploit code is available. |
| Exploit ScenarioDerived | A remote attacker could write data beyond allocated buffer boundaries leading to code execution or crashes by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability. |
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Alert meAnalysisAI
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. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
RemediationAI
A vendor patch is available. Apply the latest security update as soon as possible. Validate write boundaries, use memory-safe languages, enable compiler protections (ASLR, stack canaries).
Affects your stack
Find out whether the stacks and servers you run are on an affected version.
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
This vulnerability is classified as Out-of-bounds Write (CWE-787), which allows attackers to write data beyond allocated buffer boundaries leading to code execution or crashes. 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. Affected products include: Matrix Olm. Version information: before 3.2.3.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionNVD
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.
Threat Intelligence Overview
NVD
CVE.org
EPSS
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.
Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.
Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.
Affected Products (CPE)NVD
An issue was discovered in core/assets/form/form_question_types/form_question_type_file_upload/form_question_type_file_u
An issue was discovered in Squiz Matrix CMS 5.5.0 prior to 5.5.0.3, 5.5.1 prior to 5.5.1.8, 5.5.2 prior to 5.5.2.4, and
Unauthenticated remote attackers can coerce Conduit-derived Matrix homeservers into cryptographically signing arbitrary
matrix-appservice-irc is a Node.js IRC bridge for Matrix. Rated critical severity (CVSS 9.8), this vulnerability is remo
The olm_session_describe function in Matrix libolm before 3.2.7 is vulnerable to a buffer overflow. Rated critical sever
Matrix Synapse before 1.5.0 mishandles signature checking on some federation APIs. Rated critical severity (CVSS 9.8), t
An issue was discovered in Matrix libolm through 3.2.16. Rated medium severity (CVSS 5.3), this vulnerability is remotel
An issue was discovered in Matrix libolm through 3.2.16. Rated medium severity (CVSS 5.3), this vulnerability is remotel
An issue was discovered in Squiz Matrix before 5.3.6.1 and 5.4.x before 5.4.1.3. Rated high severity (CVSS 8.8), this vu
matrix-hookshot is a Matrix bot for connecting to external services like GitHub, GitLab, JIRA, and more. Rated critical
matrix-appservice-irc is an open source Node.js IRC bridge for Matrix. Rated high severity (CVSS 8.8), this vulnerabilit
gomatrixserverlib is a Go library for matrix protocol federation. Rated high severity (CVSS 8.8), this vulnerability is
GitHub PoC
Exploit-DB