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Vulnerability details: VCID-ttyu-4r2a-gbew
Vulnerability ID VCID-ttyu-4r2a-gbew
Aliases CVE-2019-11763
Summary 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.
Status Published
Exploitability 0.5
Weighted Severity 9.0
Risk 4.5
Affected and Fixed Packages Package Details
Weaknesses (1)
CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
System Score Found at
cvssv3 6.1 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2019-11763.json
epss 0.01291 https://api.first.org/data/v1/epss?cve=CVE-2019-11763
epss 0.01291 https://api.first.org/data/v1/epss?cve=CVE-2019-11763
epss 0.01291 https://api.first.org/data/v1/epss?cve=CVE-2019-11763
epss 0.01291 https://api.first.org/data/v1/epss?cve=CVE-2019-11763
epss 0.01291 https://api.first.org/data/v1/epss?cve=CVE-2019-11763
epss 0.01291 https://api.first.org/data/v1/epss?cve=CVE-2019-11763
epss 0.01291 https://api.first.org/data/v1/epss?cve=CVE-2019-11763
epss 0.01291 https://api.first.org/data/v1/epss?cve=CVE-2019-11763
epss 0.01291 https://api.first.org/data/v1/epss?cve=CVE-2019-11763
epss 0.01291 https://api.first.org/data/v1/epss?cve=CVE-2019-11763
epss 0.01291 https://api.first.org/data/v1/epss?cve=CVE-2019-11763
epss 0.01291 https://api.first.org/data/v1/epss?cve=CVE-2019-11763
cvssv2 4.3 https://nvd.nist.gov/vuln/detail/CVE-2019-11763
cvssv3.1 6.1 https://nvd.nist.gov/vuln/detail/CVE-2019-11763
archlinux Critical https://security.archlinux.org/AVG-1054
archlinux Critical https://security.archlinux.org/AVG-1055
generic_textual critical https://www.mozilla.org/en-US/security/advisories/mfsa2019-33
generic_textual critical https://www.mozilla.org/en-US/security/advisories/mfsa2019-34
generic_textual critical https://www.mozilla.org/en-US/security/advisories/mfsa2019-35
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2019-11763.json
https://api.first.org/data/v1/epss?cve=CVE-2019-11763
https://bugzilla.mozilla.org/show_bug.cgi?id=1584216
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-11755
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-11757
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-11759
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-11760
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-11761
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-11762
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-11763
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-11764
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-15903
https://security.gentoo.org/glsa/202003-10
https://www.mozilla.org/security/advisories/mfsa2019-33/
https://www.mozilla.org/security/advisories/mfsa2019-35/
1764444 https://bugzilla.redhat.com/show_bug.cgi?id=1764444
ASA-201910-15 https://security.archlinux.org/ASA-201910-15
ASA-201910-16 https://security.archlinux.org/ASA-201910-16
AVG-1054 https://security.archlinux.org/AVG-1054
AVG-1055 https://security.archlinux.org/AVG-1055
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*
CVE-2019-11763 https://nvd.nist.gov/vuln/detail/CVE-2019-11763
mfsa2019-33 https://www.mozilla.org/en-US/security/advisories/mfsa2019-33
mfsa2019-34 https://www.mozilla.org/en-US/security/advisories/mfsa2019-34
mfsa2019-35 https://www.mozilla.org/en-US/security/advisories/mfsa2019-35
RHSA-2019:3193 https://access.redhat.com/errata/RHSA-2019:3193
RHSA-2019:3196 https://access.redhat.com/errata/RHSA-2019:3196
RHSA-2019:3210 https://access.redhat.com/errata/RHSA-2019:3210
RHSA-2019:3237 https://access.redhat.com/errata/RHSA-2019:3237
RHSA-2019:3281 https://access.redhat.com/errata/RHSA-2019:3281
RHSA-2019:3756 https://access.redhat.com/errata/RHSA-2019:3756
USN-4165-1 https://usn.ubuntu.com/4165-1/
USN-4202-1 https://usn.ubuntu.com/4202-1/
USN-4335-1 https://usn.ubuntu.com/4335-1/
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2019-11763.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: AV:N/AC:M/Au:N/C:N/I:P/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2019-11763
Exploitability (E) Access Vector (AV) Access Complexity (AC) Authentication (Au) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

high

functional

unproven

proof_of_concept

not_defined

local

adjacent_network

network

high

medium

low

multiple

single

none

none

partial

complete

none

partial

complete

none

partial

complete
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2019-11763
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.7883
EPSS Score 0.01291
Published At Aug. 8, 2025, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2025-07-31T08:09:57.562387+00:00 Mozilla Importer Import https://github.com/mozilla/foundation-security-advisories/blob/master/announce/2019/mfsa2019-33.yml 37.0.0