Vulnerability · Published Dec 8, 2021 · Assigned by mozilla
CVE-2021-43538
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 1.2% (higher than 69% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS NVD)4.3Medium
Exploit odds (30 days)1.2%top 30.6% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known
Official description
By misusing a race in our notification code, an attacker could have forcefully hidden the notification for pages that had received full screen and pointer lock access, which could have been used for spoofing attacks. This vulnerability affects Thunderbird < 91.4.0, Firefox ESR < 91.4.0, and Firefox < 95.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:8 | firefox | 91.4.0-1.el8_5.alma | ALSA-2021:5013 |
| AlmaLinux:8 | thunderbird | 91.4.0-2.el8_5.alma | ALSA-2021:5045 |
| AlmaLinux:8 | thunderbird | 91.4.0-2.el8_5.alma.plus | ALSA-2021:5045 |
| Alpine:v3.20 | firefox | 95.0-r0 | ALPINE-CVE-2021-43538 |
| Alpine:v3.21 | firefox | 95.0-r0 | ALPINE-CVE-2021-43538 |
| Alpine:v3.22 | firefox | 95.0-r0 | ALPINE-CVE-2021-43538 |
| Alpine:v3.23 | firefox | 95.0-r0 | ALPINE-CVE-2021-43538 |
| Alpine:v3.20 | firefox-esr | 91.4.0-r0 | ALPINE-CVE-2021-43538 |
| Alpine:v3.21 | firefox-esr | 91.4.0-r0 | ALPINE-CVE-2021-43538 |
| Alpine:v3.22 | firefox-esr | 91.4.0-r0 | ALPINE-CVE-2021-43538 |
| Alpine:v3.23 | firefox-esr | 91.4.0-r0 | ALPINE-CVE-2021-43538 |
| Alpine:v3.21 | librewolf | 95.0-r0 | ALPINE-CVE-2021-43538 |
| Alpine:v3.22 | librewolf | 95.0-r0 | ALPINE-CVE-2021-43538 |
| Alpine:v3.23 | librewolf | 95.0-r0 | ALPINE-CVE-2021-43538 |
| Alpine:v3.24 | librewolf | 95.0-r0 | ALPINE-CVE-2021-43538 |
| Alpine:v3.20 | thunderbird | 91.4.0-r0 | ALPINE-CVE-2021-43538 |
| Alpine:v3.21 | thunderbird | 91.4.0-r0 | ALPINE-CVE-2021-43538 |
| Alpine:v3.22 | thunderbird | 91.4.0-r0 | ALPINE-CVE-2021-43538 |
| Alpine:v3.23 | thunderbird | 91.4.0-r0 | ALPINE-CVE-2021-43538 |
| Debian:12 | firefox-esr | 91.4.0esr-1 | DEBIAN-CVE-2021-43538 |
| Debian:13 | firefox-esr | 91.4.0esr-1 | DEBIAN-CVE-2021-43538 |
| Debian:14 | firefox-esr | 91.4.0esr-1 | DEBIAN-CVE-2021-43538 |
| Debian:12 | thunderbird | 1:91.4.0-1 | DEBIAN-CVE-2021-43538 |
| Debian:13 | thunderbird | 1:91.4.0-1 | DEBIAN-CVE-2021-43538 |
| Debian:14 | thunderbird | 1:91.4.0-1 | DEBIAN-CVE-2021-43538 |
| Rocky Linux:8 | firefox | 0:91.4.0-1.el8_5 | RLSA-2021:5013 |
| Rocky Linux:8 | thunderbird | 0:91.4.0-2.el8_5 | RLSA-2021:5045 |
| Ubuntu:22.04:LTS | firefox | 95.0+build1-0ubuntu1 | UBUNTU-CVE-2021-43538 |
| Ubuntu:22.04:LTS | mozjs78 | no fix listed | UBUNTU-CVE-2021-43538 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Thunderbird | unspecified – before 91.4.0 |
| Mozilla | Firefox ESR | unspecified – before 91.4.0 |
| Mozilla | Firefox | unspecified – before 95 |
References
- https://www.mozilla.org/security/advisories/mfsa2021-53/ x_refsource_MISC
- https://www.mozilla.org/security/advisories/mfsa2021-54/ x_refsource_MISC
- https://www.mozilla.org/security/advisories/mfsa2021-52/ x_refsource_MISC
- https://bugzilla.mozilla.org/show_bug.cgi?id=1739091 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