CVE-2019-11763
This could have led to HTML comment text being treated as HTML which could have led to XSS in a web application under certain conditions.
Does this matter?
Lower severity and a low EPSS score (1.15%). Track it; it rarely justifies an emergency change on its own.
Description
Failure to correctly handle null bytes when processing HTML entities resulted in Firefox incorrectly parsing these entities. This could have led to HTML comment text being treated as HTML which could have led to XSS in a web application under certain conditions. It could have also led to HTML entities being masked from filters - enabling the use of entities to mask the actual characters of interest from filters. This vulnerability affects Firefox < 70, Thunderbird < 68.2, and Firefox ESR < 68.2.
- CVSS 3.1
- 6.1 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- EPSS
- 1.15% probability · 67th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-79
- Affected
- mozilla/firefox · mozilla/firefox esr · mozilla/thunderbird · canonical/ubuntu linux
- Source
- security@mozilla.org
EPSS 1.1% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1584216Issue Tracking, Permissions Required
- https://security.gentoo.org/glsa/202003-10Third Party Advisory
- https://usn.ubuntu.com/4335-1/Third Party Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-33/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-34/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-35/Vendor Advisory
- https://bugzilla.mozilla.org/show_bug.cgi?id=1584216Issue Tracking, Permissions Required
- https://security.gentoo.org/glsa/202003-10Third Party Advisory
- https://usn.ubuntu.com/4335-1/Third Party Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-33/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-34/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-35/Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.