Vulnerability · Published Feb 26, 2021 · Assigned by mozilla

CVE-2021-23976

High 8.1

In plain English

A high-severity security flaw in Firefox from Mozilla. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.1% (higher than 66% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS NVD)8.1High

Exploit odds (30 days)1.1%top 34.3% of all CVEs

Exploited in the wildNo reportsnot in CISA KEV

Attack toolingNoneno public tooling known

Official description

When accepting a malicious intent from other installed apps, Firefox for Android accepted manifests from arbitrary file paths and allowed declaring webapp manifests for other origins. This could be used to gain fullscreen access for UI spoofing and could also lead to cross-origin attacks on targeted websites. Note: This issue is a different issue from CVE-2020-26954 and only affected Firefox for Android. Other operating systems are unaffected. This vulnerability affects Firefox < 86.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Alpine:v3.20	firefox	87.0-r0	ALPINE-CVE-2021-23976
Alpine:v3.21	firefox	87.0-r0	ALPINE-CVE-2021-23976
Alpine:v3.22	firefox	87.0-r0	ALPINE-CVE-2021-23976
Alpine:v3.23	firefox	87.0-r0	ALPINE-CVE-2021-23976
Alpine:v3.21	librewolf	87.0-r0	ALPINE-CVE-2021-23976
Alpine:v3.22	librewolf	87.0-r0	ALPINE-CVE-2021-23976
Alpine:v3.23	librewolf	87.0-r0	ALPINE-CVE-2021-23976
Alpine:v3.24	librewolf	87.0-r0	ALPINE-CVE-2021-23976
Ubuntu:22.04:LTS	mozjs78	no fix listed	UBUNTU-CVE-2021-23976

Affected products (as reported)

Vendor	Product	Versions
Mozilla	Firefox	< 86

References

https://www.mozilla.org/security/advisories/mfsa2021-07/ x_refsource_MISC
https://bugzilla.mozilla.org/show_bug.cgi?id=1684627 x_refsource_MISC
GLSA-202104-10 vendor-advisory, x_refsource_GENTOO