CVE-2020-26955

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Summary

CVECVE-2020-26955
StatePUBLISHED
Assignermozilla
Source PriorityCVE Program / NVD first with legacy fallback
Published2020-12-09 01:15:12 UTC
Updated2026-08-19 15:29:21 UTC
DescriptionWhen a user downloaded a file in Firefox for Android, if a cookie is set, it would have been re-sent during a subsequent file download operation on the same domain, regardless of whether the original and subsequent request were in private and non-private browsing modes. *Note: This issue only affected Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 83.

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

EPSS: 0.008200000 probability, percentile 0.543980000 (date 2026-08-19)

Problem Types: CWE-565 | Cookies set during file downloads are shared between normal and Private Browsing Mode in Firefox for Android

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
2.0[email protected]Primary4.3AV:N/AC:M/Au:N/C:N/I:P/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

CVSS v2.0 Breakdown

Access Vector
Network
Access Complexity
Medium
Authentication
None
Confidentiality
None
Integrity
Partial
Availability
None

AV:N/AC:M/Au:N/C:N/I:P/A:N

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Mozilla Firefox Mobile All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mozilla Firefox affected < 83 Not specified

References

ReferenceSourceLinkTags
Security Vulnerabilities fixed in Firefox 83 — Mozilla af854a3a-2127-422b-91ae-364da2661108 www.mozilla.org Vendor Advisory
1663261 - (CVE-2020-26955) Fenix file download request shares private browsing mode cookie af854a3a-2127-422b-91ae-364da2661108 bugzilla.mozilla.org Issue Tracking, Permissions Required, Vendor Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Legacy QID Mappings

  • 500957 Alpine Linux Security Update for firefox
  • 503842 Alpine Linux Security Update for firefox

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