CVE-2021-29958
When a download was initiated, the client did not check whether it was in normal or private...
When a download was initiated, the client did not check whether it was in normal or private browsing mode, which led to private mode cookies being shared in normal browsing mode. This vulnerability affects Firefox for iOS < 34.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Required
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
When a download was initiated, the client did not check whether it was in normal or private browsing mode, which led to private mode cookies being shared in normal browsing mode. This vulnerability affects Firefox for iOS < 34.
- Record
CVE-2021-29958- CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N - CVSS 2.0
- 4.3 Medium
AV:N/AC:M/Au:N/C:P/I:N/A:N - Weakness
- CWE-862
- Updated
- 2026-11-02
CVE List No score
When a download was initiated, the client did not check whether it was in normal or private browsing mode, which led to private mode cookies being shared in normal browsing mode. This vulnerability affects Firefox for iOS < 34.
- Record
CVE-2021-29958- Updated
- 2026-11-02
EUVDEUVD-2021-16417 No score
When a download was initiated, the client did not check whether it was in normal or private browsing mode, which led to private mode cookies being shared in normal browsing mode. This vulnerability affects Firefox for iOS < 34.
- Record
EUVD-2021-16417- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-5j3q-vmj5-h7fx
When a download was initiated, the client did not check whether it was in normal or private...
When a download was initiated, the client did not check whether it was in normal or private browsing mode, which led to private mode cookies being shared in normal browsing mode. This vulnerability affects Firefox for iOS < 34.
- Record
GHSA-5j3q-vmj5-h7fx- CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N - Weakness
- CWE-668
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-29958 is a medium vulnerability (CVSS 4.3) in Mozilla Firefox, published June 24, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.67%, the 52nd percentile. No source names a fixed version.