CVE-2021-29958

mediumpriority · track · 17OT risk · elevatedEPSS 0.007 · 52 %ileEURUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.67% (52nd) EPSS

CVSS 4.3 · medium

Is it mine?

3 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · fstec_bdu · nvd

EPSS · scored 2026-10-27

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.

cvss

Technical severity, 0–10. One row per scoring source.

4.3

010

base score 0–10 · higher = more severe · hover a vector to decode

v2.04.3mediumAV:N/AC:M/Au:N/C:P/I:N/A:Nprimary · NVD / NIST USexploitability 8.6 · impact 2.9

v3.14.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:Nprimary · NVD / NIST USexploitability 2.8 · impact 1.4

v3.14.3mediumAV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:Nsecondary · FSTEC (BDU) RU

v3.14mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-862USprimaryCWE-862US

affected products (3)

Products and version ranges known to be affected.

Mozilla Firefox for iOSunspecified → 34enisa_euvdEU
Mozilla Corp. Firefox≤ 34.0fstec_bduRU
mozilla firefox< 34.0nvdUScpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*

also known as (4)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu nvd NVD CVE.org MITRE

published 2021-06-24modified 2026-06-17

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+11478 more

references (8)

External citations — patches, advisories, analysis.

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