High severity · published Jun 24, 2021
CVE-2021-29946
Ports that were written as an integer overflow above the bounds of a 16-bit integer could have bypassed port blocking restrictions when used in the Alt-Svc header
8.8
CVSS
1.3%
EPSS
No
On KEV
Description
Ports that were written as an integer overflow above the bounds of a 16-bit integer could have bypassed port blocking restrictions when used in the Alt-Svc header. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)1.3% · higher than 70% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FI
Firefox · Mozilla
before 88.0 · source: NVD
FE
Firefox Esr · Mozilla
before 78.10 · source: NVD
TH
Thunderbird · Mozilla
before 78.10 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-29946
CVE.org
https://www.cve.org/CVERecord?id=CVE-2021-29946
Permissions Required
https://bugzilla.mozilla.org/show_bug.cgi?id=1698503
Release Notes
https://www.mozilla.org/security/advisories/mfsa2021-14/
Release Notes
https://www.mozilla.org/security/advisories/mfsa2021-15/
Release Notes
https://www.mozilla.org/security/advisories/mfsa2021-16/
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