Vulnerability · Published Dec 8, 2021 · Assigned by mozilla
CVE-2021-43542
Medium 6.5
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 1.8% (higher than 79% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS NVD)6.5Medium
Exploit odds (30 days)1.8%top 21.0% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known
Official description
Using XMLHttpRequest, an attacker could have identified installed applications by probing error messages for loading external protocols. 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-2021-43542 |
| Alpine:v3.21 | firefox | 95.0-r0 | ALPINE-CVE-2021-43542 |
| Alpine:v3.22 | firefox | 95.0-r0 | ALPINE-CVE-2021-43542 |
| Alpine:v3.23 | firefox | 95.0-r0 | ALPINE-CVE-2021-43542 |
| Alpine:v3.20 | firefox-esr | 91.4.0-r0 | ALPINE-CVE-2021-43542 |
| Alpine:v3.21 | firefox-esr | 91.4.0-r0 | ALPINE-CVE-2021-43542 |
| Alpine:v3.22 | firefox-esr | 91.4.0-r0 | ALPINE-CVE-2021-43542 |
| Alpine:v3.23 | firefox-esr | 91.4.0-r0 | ALPINE-CVE-2021-43542 |
| Alpine:v3.21 | librewolf | 95.0-r0 | ALPINE-CVE-2021-43542 |
| Alpine:v3.22 | librewolf | 95.0-r0 | ALPINE-CVE-2021-43542 |
| Alpine:v3.23 | librewolf | 95.0-r0 | ALPINE-CVE-2021-43542 |
| Alpine:v3.24 | librewolf | 95.0-r0 | ALPINE-CVE-2021-43542 |
| Alpine:v3.20 | thunderbird | 91.4.0-r0 | ALPINE-CVE-2021-43542 |
| Alpine:v3.21 | thunderbird | 91.4.0-r0 | ALPINE-CVE-2021-43542 |
| Alpine:v3.22 | thunderbird | 91.4.0-r0 | ALPINE-CVE-2021-43542 |
| Alpine:v3.23 | thunderbird | 91.4.0-r0 | ALPINE-CVE-2021-43542 |
| Debian:12 | firefox-esr | 91.4.0esr-1 | DEBIAN-CVE-2021-43542 |
| Debian:13 | firefox-esr | 91.4.0esr-1 | DEBIAN-CVE-2021-43542 |
| Debian:14 | firefox-esr | 91.4.0esr-1 | DEBIAN-CVE-2021-43542 |
| Debian:12 | thunderbird | 1:91.4.0-1 | DEBIAN-CVE-2021-43542 |
| Debian:13 | thunderbird | 1:91.4.0-1 | DEBIAN-CVE-2021-43542 |
| Debian:14 | thunderbird | 1:91.4.0-1 | DEBIAN-CVE-2021-43542 |
| 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-2021-43542 |
| Ubuntu:22.04:LTS | mozjs78 | no fix listed | UBUNTU-CVE-2021-43542 |
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=1723281 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