league/commonmark vulnerabilities
Summary
It was discovered that league/commonmark did not properly restrict unsafe attributes when the Attributes extension was enabled. An attacker could possibly use this issue to cause cross-site scripting by injecting malicious code into rendered HTML. This issue only affected Ubuntu 22.04 LTS and Ubuntu 24.04 LTS. (CVE-2025-46734) It was discovered that league/commonmark did not properly block certain disallowed HTML tags in some cases. An attacker could possibly use this issue to cause cross-site scripting by inserting malicious HTML that bypassed filtering. (CVE-2026-30838) It was discovered that league/commonmark did not properly enforce domain allowlist checks in the Embed extension. An attacker could possibly use this issue to bypass domain restrictions and cause untrusted content to be treated as allowed. This issue only affected Ubuntu 24.04 LTS. (CVE-2026-33347) Affected Ubuntu releases: 24.04, 22.04, 20.04. CVEs: CVE-2026-33347, CVE-2025-46734, CVE-2026-30838.
- Ubuntu 24.04
- Ubuntu 22.04
- Ubuntu 20.04
Official advisory · medium-confidence parse· fetched 3 hours ago·verify at source
Mitigation checklist
- Apply available updates: `sudo apt update && sudo apt upgrade` (a standard system update installs the fix).
Official advisory · medium-confidence parse· fetched 3 hours ago·verify at source
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