Advisory Database
  • Advisories
  • Dependency Scanning
  1. pypi
  2. ›
  3. matrix-synapse
  4. ›
  5. CVE-2021-21333

CVE-2021-21333: HTML injection in email and account expiry notifications

March 26, 2021 (updated September 30, 2024)

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.

References

  • github.com/advisories/GHSA-c5f8-35qr-q4fm
  • github.com/matrix-org/synapse
  • github.com/matrix-org/synapse/commit/e54746bdf7d5c831eabe4dcea76a7626f1de73df
  • github.com/matrix-org/synapse/pull/9200
  • github.com/matrix-org/synapse/releases/tag/v1.27.0
  • github.com/matrix-org/synapse/security/advisories/GHSA-c5f8-35qr-q4fm
  • github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2021-134.yaml
  • lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/TNNAJOZNMVMXM6AS7RFFKB4QLUJ4IFEY
  • nvd.nist.gov/vuln/detail/CVE-2021-21333

Code Behaviors & Features

Detect and mitigate CVE-2021-21333 with GitLab Dependency Scanning

Secure your software supply chain by verifying that all open source dependencies used in your projects contain no disclosed vulnerabilities. Learn more about Dependency Scanning →

Affected versions

All versions before 1.27.0

Fixed versions

  • 1.27.0

Solution

Upgrade to version 1.27.0 or above.

Impact 6.1 MEDIUM

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

Learn more about CVSS

Weakness

  • CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
  • CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Source file

pypi/matrix-synapse/CVE-2021-21333.yml

Spotted a mistake? Edit the file on GitLab.

  • Site Repo
  • About GitLab
  • Terms
  • Privacy Statement
  • Contact

Page generated Wed, 14 May 2025 12:15:07 +0000.