Vulnerability · Published Dec 8, 2021 · Assigned by mozilla
CVE-2021-38506
Medium 4.3
In plain English
A medium-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 1.5% (higher than 75% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS NVD)4.3Medium
Exploit odds (30 days)1.5%top 25.5% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known
Official description
Through a series of navigations, Firefox could have entered fullscreen mode without notification or warning to the user. This could lead to spoofing attacks on the browser UI including phishing. This vulnerability affects Firefox < 94, Thunderbird < 91.3, and Firefox ESR < 91.3.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:8 | firefox | 91.3.0-1.el8_4.alma | ALSA-2021:4123 |
| AlmaLinux:8 | thunderbird | 91.3.0-2.el8_4.alma | ALSA-2021:4130 |
| AlmaLinux:8 | thunderbird | 91.3.0-2.el8_4.alma.plus | ALSA-2021:4130 |
| Alpine:v3.20 | firefox | 94.0-r0 | ALPINE-CVE-2021-38506 |
| Alpine:v3.21 | firefox | 94.0-r0 | ALPINE-CVE-2021-38506 |
| Alpine:v3.22 | firefox | 94.0-r0 | ALPINE-CVE-2021-38506 |
| Alpine:v3.23 | firefox | 94.0-r0 | ALPINE-CVE-2021-38506 |
| Alpine:v3.20 | firefox-esr | 91.3.0-r0 | ALPINE-CVE-2021-38506 |
| Alpine:v3.21 | firefox-esr | 91.3.0-r0 | ALPINE-CVE-2021-38506 |
| Alpine:v3.22 | firefox-esr | 91.3.0-r0 | ALPINE-CVE-2021-38506 |
| Alpine:v3.23 | firefox-esr | 91.3.0-r0 | ALPINE-CVE-2021-38506 |
| Alpine:v3.21 | librewolf | 94.0-r0 | ALPINE-CVE-2021-38506 |
| Alpine:v3.22 | librewolf | 94.0-r0 | ALPINE-CVE-2021-38506 |
| Alpine:v3.23 | librewolf | 94.0-r0 | ALPINE-CVE-2021-38506 |
| Alpine:v3.24 | librewolf | 94.0-r0 | ALPINE-CVE-2021-38506 |
| Alpine:v3.20 | thunderbird | 91.3.2-r0 | ALPINE-CVE-2021-38506 |
| Alpine:v3.21 | thunderbird | 91.3.2-r0 | ALPINE-CVE-2021-38506 |
| Alpine:v3.22 | thunderbird | 91.3.2-r0 | ALPINE-CVE-2021-38506 |
| Alpine:v3.23 | thunderbird | 91.3.2-r0 | ALPINE-CVE-2021-38506 |
| Debian:12 | firefox-esr | 91.3.0esr-1 | DEBIAN-CVE-2021-38506 |
| Debian:13 | firefox-esr | 91.3.0esr-1 | DEBIAN-CVE-2021-38506 |
| Debian:14 | firefox-esr | 91.3.0esr-1 | DEBIAN-CVE-2021-38506 |
| Debian:12 | thunderbird | 1:91.3.0-1 | DEBIAN-CVE-2021-38506 |
| Debian:13 | thunderbird | 1:91.3.0-1 | DEBIAN-CVE-2021-38506 |
| Debian:14 | thunderbird | 1:91.3.0-1 | DEBIAN-CVE-2021-38506 |
| Rocky Linux:8 | firefox | 0:91.3.0-1.el8 | RLSA-2021:4123 |
| Rocky Linux:8 | thunderbird | 0:91.3.0-2.el8 | RLSA-2021:4130 |
| Rocky Linux:8 | thunderbird | 0:91.3.0-2.el8_4 | RLSA-2021:4130 |
| Ubuntu:22.04:LTS | firefox | 94.0+build3-0ubuntu1 | UBUNTU-CVE-2021-38506 |
| Ubuntu:22.04:LTS | mozjs78 | no fix listed | UBUNTU-CVE-2021-38506 |
| Ubuntu:22.04:LTS | thunderbird | 1:91.3.1+build1-0ubuntu1 | UBUNTU-CVE-2021-38506 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | unspecified – before 94 |
| Mozilla | Thunderbird | unspecified – before 91.3 |
| Mozilla | Firefox ESR | unspecified – before 91.3 |
References
- https://www.mozilla.org/security/advisories/mfsa2021-49/ x_refsource_MISC
- https://www.mozilla.org/security/advisories/mfsa2021-50/ x_refsource_MISC
- https://www.mozilla.org/security/advisories/mfsa2021-48/ x_refsource_MISC
- https://bugzilla.mozilla.org/show_bug.cgi?id=1730750 x_refsource_MISC
- DSA-5026 vendor-advisory, x_refsource_DEBIAN
- [debian-lts-announce] 20211229 [SECURITY] [DLA 2863-1] firefox-esr security update mailing-list, x_refsource_MLIST
- DSA-5034 vendor-advisory, x_refsource_DEBIAN
- [debian-lts-announce] 20220104 [SECURITY] [DLA 2874-1] thunderbird security update mailing-list, x_refsource_MLIST
- GLSA-202202-03 vendor-advisory, x_refsource_GENTOO
- GLSA-202208-14 vendor-advisory, x_refsource_GENTOO