Vulnerability Details : CVE-2021-21333
Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP. In Synapse before version 1.27.0, the notification emails sent for notifications for missed messages or for an expiring account are subject to HTML injection. In the case of the notification for missed messages, this could allow an attacker to insert forged content into the email. The account expiry feature is not enabled by default and the HTML injection is not controllable by an attacker. This is fixed in version 1.27.0.
Vulnerability category: Cross site scripting (XSS)
Products affected by CVE-2021-21333
- cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:*
- cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
Exploit prediction scoring system (EPSS) score for CVE-2021-21333
0.54%
Probability of exploitation activity in the next 30 days
EPSS Score History
~ 65 %
Percentile, the proportion of vulnerabilities that are scored at or less
CVSS scores for CVE-2021-21333
| Base Score | Base Severity | CVSS Vector | Exploitability Score | Impact Score | Score Source | First Seen |
|---|---|---|---|---|---|---|
|
2.6
|
LOW | AV:N/AC:H/Au:N/C:N/I:P/A:N |
4.9
|
2.9
|
NIST | |
|
6.1
|
MEDIUM | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N |
1.6
|
4.0
|
NIST | |
|
6.1
|
MEDIUM | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N |
1.6
|
4.0
|
GitHub, Inc. |
CWE ids for CVE-2021-21333
-
The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.Assigned by: security-advisories@github.com (Secondary)
-
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.Assigned by: nvd@nist.gov (Primary)
References for CVE-2021-21333
-
https://github.com/matrix-org/synapse/releases/tag/v1.27.0
Release v1.27.0 · matrix-org/synapse · GitHubThird Party Advisory
-
https://github.com/matrix-org/synapse/security/advisories/GHSA-c5f8-35qr-q4fm
HTML injection in email and account expiry notifications · Advisory · matrix-org/synapse · GitHubPatch;Third Party Advisory
-
https://github.com/matrix-org/synapse/commit/e54746bdf7d5c831eabe4dcea76a7626f1de73df
Clean-up the template loading code. (#9200) · matrix-org/synapse@e54746b · GitHubPatch;Third Party Advisory
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https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/TNNAJOZNMVMXM6AS7RFFKB4QLUJ4IFEY/
[SECURITY] Fedora 34 Update: matrix-synapse-1.38.1-1.fc34 - package-announce - Fedora Mailing-ListsMailing List;Third Party Advisory
-
https://github.com/matrix-org/synapse/pull/9200
Clean-up the template loading code by clokep · Pull Request #9200 · matrix-org/synapse · GitHubPatch;Third Party Advisory
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