CVE-2021-29946
HIGH
8.8
CVSS Score
Published: June 24, 2021 at 01:19 PM UTC
Updated: June 17, 2026 at 03:48 AM UTC
3 products affected across 1 vendorFirefoxThunderbirdFirefox ESR
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Severity
HIGH8.8
Exploit prediction
EPSS 1%
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.
Affected
Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.
v < 88
Affected range stops below 88, so it looks safe — our inference, not a vendor statement
Affected range stops below 88.0, so it looks safe — our inference, not a vendor statement
v < 78.10
Affected range stops below 78.10, so it looks safe — our inference, not a vendor statement
v < 78.10
Affected range stops below 78.10, so it looks safe — our inference, not a vendor statement
Remediation
No guide yetNo remediation guidance has been written for this CVE yet. What the record does show:
References (4)
x_refsource_MISCPermissions RequiredVendor Advisory
Source: [email protected]
https://bugzilla.mozilla.org/show_bug.cgi?id=1698503x_refsource_MISCRelease NotesVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2021-14/x_refsource_MISCRelease NotesVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2021-15/x_refsource_MISCRelease NotesVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2021-16/CVSS
- Attack Vector
- NETWORK
- Complexity
- LOW
- Privileges
- NONE
- User Interaction
- REQUIRED
- Scope
- UNCHANGED
- Confidentiality
- HIGH
- Integrity
- HIGH
- Availability
- HIGH
Vector?
Quick Info
StatusMODIFIED
CWE
CWE-190
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