CVE-2016-1960Firefox Vulnerability
Integer underflow in the nsHtml5TreeBuilder class in the HTML5 string parser in Mozilla Firefox before 45.0 and Firefox ESR 38.x before 38.7 allows remote attackers to execute arbitrary code or cause a denial of service (use-after-free) by leveraging mishandling of end tags, as…
Published Mar 13, 2016 · Updated Aug 4, 2026 · Also known as DEBIAN-CVE-2016-1960, UBUNTU-CVE-2016-1960
Key Facts
Patch immediately- CVE-2016-1960 is a high-severity vulnerability (CVSS 8.8 v3.1) affecting Firefox (Mozilla), Thunderbird (Mozilla), Leap (Opensuse) and 22 more products.
- It is not listed in any known-exploited vulnerabilities catalog. A public exploit is reported by tracking sources, but no code link is listed yet.
- EPSS estimates a 31% probability of exploitation in the next 30 days.
- Fixed versions are available, including Firefox 0:38.7.0-1.el5_11, Firefox 0:38.7.0-1.el6_7, Firefox 0:38.7.0-1.el7_2.
- Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
Scores
CVSS v3.1
8.8
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
31%
Higher than 98.2% of all scored CVEs
Exploit maturity
Proof of concept
ATLAS score
47/100
Publication score, see How it works
Exploitation Verdict
KEV listed
Not listed
Federal due date
None
No federal due date
Ransomware use
Not reported
Attributed actors
None named
Exploit & Defence Guidance
Exploit maturity
Proof of concept
Public exploit code
2
Proof-of-concept links
In-the-wild evidence
0
Reports of active use
Advisories And Exploit References
Description
Integer underflow in the nsHtml5TreeBuilder class in the HTML5 string parser in Mozilla Firefox before 45.0 and Firefox ESR 38.x before 38.7 allows remote attackers to execute arbitrary code or cause a denial of service (use-after-free) by leveraging mishandling of end tags, as demonstrated by incorrect SVG processing, aka ZDI-CAN-3545.
Affected Products
331 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| FirefoxMozilla | 38.0, 38.0.1, 38.0.5, 38.1.0, 38.1.1, 38.2.0, 38.2.1, 38.3.0 | 44.0.2 |
| ThunderbirdMozilla | See advisory | 38.6.0 |
| LeapOpensuse | 42.1 | n/a |
| OpensuseOpensuse | 13.1, 13.2 | n/a |
| LinuxOracle | 5.0, 6, 7 | n/a |
Patched Releases
Firefox
0:38.7.0-1.el5_11, 0:38.7.0-1.el6_7, 0:38.7.0-1.el7_2, 38.7.0-1.0.1.el5_11, 38.7.0-1.0.1.el6_7, 38.7.0-1.0.1.el7_2, 45.0-1, 45.0+build2-0ubuntu0.14.04.1, 44.0.2
firefox-esr
128.5.1-1.1, 45.0esr-1
firefox-esr-branding-upstream
128.5.1-1.1
firefox-esr-translations-common
128.5.1-1.1
firefox-esr-translations-other
128.5.1-1.1
icedove
38.7.0-1~deb7u1, 38.7.0-1~deb8u1
iceweasel
38.7.0esr-1~deb7u1, 38.7.0esr-1~deb8u1
libfreebl3
3.20.2-20.1, 3.20.2-28.1, 3.20.2-40.1, 3.21.1-12.1
libfreebl3-32bit
3.20.2-20.1, 3.20.2-28.1, 3.20.2-40.1, 3.21.1-12.1
libfreebl3-hmac
3.20.2-40.1
libfreebl3-hmac-32bit
3.20.2-40.1
libfreebl3-x86
3.20.2-28.1
libsoftokn3
3.20.2-28.1, 3.20.2-40.1, 3.21.1-12.1
libsoftokn3-32bit
3.20.2-28.1, 3.20.2-40.1, 3.21.1-12.1
libsoftokn3-hmac
3.20.2-40.1
libsoftokn3-hmac-32bit
3.20.2-40.1
libsoftokn3-x86
3.20.2-28.1
Thunderbird
38.6.0, 0:38.7.0-1.el5_11, 0:38.7.0-1.el6_7, 0:38.7.0-1.el7_2, 1:38.7.2+build1-0ubuntu0.14.04.1, 1:38.7.2+build1-0ubuntu0.16.04.1, 38.7.0-1.0.1.el5_11, 38.7.0-1.0.1.el6_7, 38.7.0-1.0.1.el7_2
mozilla-nspr
4.12-10.1, 4.12-12.1, 4.12-19.1, 4.12-24.1
mozilla-nspr-32bit
4.12-10.1, 4.12-12.1, 4.12-19.1, 4.12-24.1
mozilla-nspr-devel
4.12-10.1, 4.12-12.1, 4.12-19.1, 4.12-24.1
mozilla-nspr-x86
4.12-24.1
mozilla-nss
3.20.2-20.1, 3.20.2-28.1, 3.20.2-40.1, 3.21.1-12.1
mozilla-nss-32bit
3.20.2-20.1, 3.20.2-28.1, 3.20.2-40.1, 3.21.1-12.1
mozilla-nss-certs
3.20.2-40.1, 3.21.1-12.1
Timeline
Publicly disclosed
Mar 13, 2016
Last updated
Aug 4, 2026
References
- advisorysecurity-tracker.debian.org · CVE-2016-1960
- advisoryubuntu.com · CVE-2016-1960
- advisorycve.org · CVERecord
- advisoryopenSUSE-SU-2016:0894
- advisoryopenSUSE-SU-2016:1767
FAQ
Common Questions.
Integer underflow in the nsHtml5TreeBuilder class in the HTML5 string parser in Mozilla Firefox before 45.0 and Firefox ESR 38.x before 38.7 allows remote attackers to execute arbitrary code or cause a denial of service (use-after-free) by leveraging mishandling of end tags, as demonstrated by incorrect SVG processing…
Affected: Firefox (Mozilla) versions 38.0, 38.0.1, 38.0.5, 38.1.0, 38.1.1, 38.2.0, 38.2.1, 38.3.0; Thunderbird (Mozilla); Leap (Opensuse) versions 42.1, among others. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
A public exploit is reported by tracking sources, but no code link is listed yet.
Fixed versions are available, including Firefox 0:38.7.0-1.el5_11, Firefox 0:38.7.0-1.el6_7, Firefox 0:38.7.0-1.el7_2.
Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
Is CVE-2016-1960 On Your Attack Surface?
Brandefense matches it against the products discovered on your perimeter and opens a finding the day a CVE like this is listed.
Request A Demo