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CVE-2021-29987

MEDIUM
6.5
CVSS Score
Published: August 17, 2021 at 07:12 PM UTC
Updated: June 17, 2026 at 03:48 AM UTC
2 products affected across 1 vendorFirefoxThunderbird· also runs on 1 platform

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.9%

Description

After requesting multiple permissions, and closing the first permission panel, subsequent permission panels will be displayed in a different position but still record a click in the default location, making it possible to trick a user into accepting a permission they did not want to. *This bug only affects Firefox on Linux. Other operating systems are unaffected.*. This vulnerability affects Firefox < 91 and Thunderbird < 91.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Firefox· Mozilla
95%
v < 91
Affected range stops below 91, so it looks safe — our inference, not a vendor statement
Affected range stops below 91.0, so it looks safe — our inference, not a vendor statement
linux-linux-kernel (environment)
Thunderbird· Mozilla
95%
v < 91
Affected range stops below 91, so it looks safe — our inference, not a vendor statement
Affected range stops below 91.0, so it looks safe — our inference, not a vendor statement
linux-linux-kernel (environment)

Runs on — not affected

The affected product only carries this flaw when running on these platforms. The platforms themselves are not vulnerable.

References (4)

x_refsource_MISCIssue TrackingVendor Advisory
Source: [email protected]
https://bugzilla.mozilla.org/show_bug.cgi?id=1716129
Vendor Advisoryx_refsource_GENTOOThird Party Advisory
Source: [email protected]
https://security.gentoo.org/glsa/202202-03
x_refsource_MISCVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2021-33/
x_refsource_MISCVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2021-36/

CVSS

6.5MEDIUM[email protected]
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-307

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