CVE-2019-17016: XSS
Last updated 25 August 2025
Other sources
When pasting a <style> 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.
— Launchpad
When pasting a <style> 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.
External Reference:
https://www.mozilla.org/en-US/security/advisories/mfsa2020-02/#CVE-2019-17016
— Red Hat
When pasting a <style> 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.
— Mozilla
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
redhat/firefoxto a version that resolves this vulnerability.Fixed in 68.4 - Upgrade
Upgrade
redhat/thunderbirdto a version that resolves this vulnerability.Fixed in 68.4.1 - Upgrade
Upgrade
Thunderbirdto a version that resolves this vulnerability.Fixed in 68.4.1 - Upgrade
Upgrade
Firefoxto a version that resolves this vulnerability.Fixed in 72 - Upgrade
Upgrade
Firefox ESRto a version that resolves this vulnerability.Fixed in 68.4 - Upgrade
Upgrade
debian/firefoxto a version that resolves this vulnerability.Fixed in 149.0.2-1 - Upgrade
Upgrade
debian/firefox-esrto a version that resolves this vulnerability.Fixed in 115.14.0esr-1~deb11u1Fixed in 140.9.1esr-1~deb11u1Fixed in 128.14.0esr-1~deb12u1Fixed in 140.9.1esr-1~deb12u1Fixed in 140.8.0esr-1~deb13u1Fixed in 140.9.1esr-1~deb13u1Fixed in 140.9.1esr-1 - Upgrade
Upgrade
debian/thunderbirdto a version that resolves this vulnerability.Fixed in 1:115.12.0-1~deb11u1Fixed in 1:140.9.1esr-1~deb11u1Fixed in 1:140.6.0esr-1~deb12u1Fixed in 1:140.9.1esr-1~deb12u1Fixed in 1:140.8.0esr-1~deb13u1Fixed in 1:140.9.1esr-1~deb13u1Fixed in 1:140.9.0esr-1Fixed in 1:140.9.1esr-1 - Upgrade
Upgrade
alpine/firefoxto a version that resolves this vulnerability.Fixed in 71.0.1-r0 - Upgrade
Upgrade
alpine/firefox-esrto a version that resolves this vulnerability.Fixed in 68.4.1-r0 - Upgrade
Upgrade
alpine/librewolfto a version that resolves this vulnerability.Fixed in 71.0.1-r0
Event History
Parent advisories
This vulnerability appears in the following advisories.
Peer vulnerabilities
Found alongside the following vulnerabilities.
Frequently Asked Questions
What is the vulnerability ID for this issue?
The vulnerability ID for this issue is CVE-2019-17016.
What is the title of this vulnerability?
The title of this vulnerability is 'When pasting a <style> tag from the clipboard into a rich text editor the CSS sanitizer incorrectly rewrites a @namespace rule.'
What is the severity of CVE-2019-17016?
The severity of CVE-2019-17016 is high (7).
Which software products are affected by CVE-2019-17016?
The software products affected by CVE-2019-17016 are Mozilla Firefox ESR 68.4, Mozilla Firefox 72, and Mozilla Thunderbird 68.4.1.
How can this vulnerability be exploited?
This vulnerability can be exploited by pasting a <style> tag from the clipboard into a rich text editor.