CVE-2026-100820
Privilege escalation in the Address Bar component
HIGH
8.8
CVSS Score
Published: September 29, 2026 at 12:36 PM UTC
Updated: October 5, 2026 at 02:06 PM UTC
2 products affected across 1 vendorFirefoxThunderbird
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Severity
HIGH8.8
Exploit prediction
EPSS 0.2%
SSVC
No known exploit
Description
Privilege escalation in the Address Bar component. This vulnerability was fixed in Firefox ESR 153.4, Firefox 157, and Firefox ESR 140.17.
Affected
Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.
v < 140.17.0141.0 ≤ v < 153.4.0154.0.0 ≤ v < 157.0.0
Vendor states this is fixed in 140.17 (unaffected)
Affected range stops below 140.17.0, so it looks safe — our inference, not a vendor statement
Vendor states this is fixed in 153.4 (unaffected)
Affected range stops below 153.4.0, so it looks safe — our inference, not a vendor statement
Vendor states this is fixed in 157 (unaffected)
Affected range stops below 157.0.0, so it looks safe — our inference, not a vendor statement
v < 140.17.0141.0 ≤ v < 153.4.0154.0 ≤ v < 157.0
Vendor states this is fixed in 140.17 (unaffected)
Affected range stops below 140.17.0, so it looks safe — our inference, not a vendor statement
Vendor states this is fixed in 153.4 (unaffected)
Affected range stops below 153.4.0, so it looks safe — our inference, not a vendor statement
Vendor states this is fixed in 157 (unaffected)
Affected range stops below 157.0, 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:
Patch and advisory references
References (7)
SSVC — Action Prioritization
SSVCNo known exploitNot automatableTotal impact
SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.
CVSS
8.8HIGHCISA-ADP
- Attack Vector
- NETWORK
- Complexity
- LOW
- Privileges
- NONE
- User Interaction
- REQUIRED
- Scope
- UNCHANGED
- Confidentiality
- HIGH
- Integrity
- HIGH
- Availability
- HIGH
Vector?
Quick Info
StatusANALYZED
CWE
CWE-269
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