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Vulnerability details: VCID-mwm6-1d7e-mfev
Vulnerability ID VCID-mwm6-1d7e-mfev
Aliases CVE-2021-40824
GHSA-jjmc-4p83-pp26
Summary Use of a Broken or Risky Cryptographic Algorithm A logic error in the room key sharing functionality of Element Android exists. This error allows the attacker to decrypt end-to-end encrypted messages sent by affected clients.
Status Published
Exploitability 0.5
Weighted Severity 6.2
Risk 3.1
Affected and Fixed Packages Package Details
Weaknesses (3)
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
CWE-327 Use of a Broken or Risky Cryptographic Algorithm
System Score Found at
epss 0.00239 https://api.first.org/data/v1/epss?cve=CVE-2021-40824
epss 0.00239 https://api.first.org/data/v1/epss?cve=CVE-2021-40824
epss 0.00239 https://api.first.org/data/v1/epss?cve=CVE-2021-40824
epss 0.00239 https://api.first.org/data/v1/epss?cve=CVE-2021-40824
epss 0.00239 https://api.first.org/data/v1/epss?cve=CVE-2021-40824
epss 0.00239 https://api.first.org/data/v1/epss?cve=CVE-2021-40824
epss 0.00239 https://api.first.org/data/v1/epss?cve=CVE-2021-40824
epss 0.00239 https://api.first.org/data/v1/epss?cve=CVE-2021-40824
epss 0.00239 https://api.first.org/data/v1/epss?cve=CVE-2021-40824
epss 0.00239 https://api.first.org/data/v1/epss?cve=CVE-2021-40824
epss 0.00239 https://api.first.org/data/v1/epss?cve=CVE-2021-40824
epss 0.00239 https://api.first.org/data/v1/epss?cve=CVE-2021-40824
cvssv3.1_qr MODERATE https://github.com/advisories/GHSA-jjmc-4p83-pp26
cvssv3.1 5.9 https://github.com/matrix-org/matrix-android-sdk2/releases/tag/v1.2.2
generic_textual MODERATE https://github.com/matrix-org/matrix-android-sdk2/releases/tag/v1.2.2
cvssv3.1 5.9 https://matrix.org/blog/2021/09/13/vulnerability-disclosure-key-sharing
generic_textual MODERATE https://matrix.org/blog/2021/09/13/vulnerability-disclosure-key-sharing
cvssv3.1 5.9 https://nvd.nist.gov/vuln/detail/CVE-2021-40824
generic_textual MODERATE https://nvd.nist.gov/vuln/detail/CVE-2021-40824
Reference id Reference type URL
https://api.first.org/data/v1/epss?cve=CVE-2021-40824
https://github.com/matrix-org/matrix-android-sdk2/releases/tag/v1.2.2
https://matrix.org/blog/2021/09/13/vulnerability-disclosure-key-sharing
CVE-2021-40824 https://nvd.nist.gov/vuln/detail/CVE-2021-40824
GHSA-jjmc-4p83-pp26 https://github.com/advisories/GHSA-jjmc-4p83-pp26
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Found at https://github.com/matrix-org/matrix-android-sdk2/releases/tag/v1.2.2
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Found at https://matrix.org/blog/2021/09/13/vulnerability-disclosure-key-sharing
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2021-40824
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.46949
EPSS Score 0.00239
Published At April 1, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-04-01T12:48:50.805494+00:00 GitLab Importer Import https://gitlab.com/gitlab-org/advisories-community/-/blob/main/maven/org.matrix.android/matrix-android-sdk2/CVE-2021-40824.yml 38.0.0