Vulnerability · Published Dec 8, 2021 · Assigned by mozilla
CVE-2021-43535
High 8.8
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 67% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS NVD)8.8High
Exploit odds (30 days)1.1%top 33.1% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known
Official description
A use-after-free could have occured when an HTTP2 session object was released on a different thread, leading to memory corruption and a potentially exploitable crash. This vulnerability affects Firefox < 93, Thunderbird < 91.3, and Firefox ESR < 91.3.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | thunderbird | 91.3.2-r0 | ALPINE-CVE-2021-43535 |
| Alpine:v3.21 | thunderbird | 91.3.2-r0 | ALPINE-CVE-2021-43535 |
| Alpine:v3.22 | thunderbird | 91.3.2-r0 | ALPINE-CVE-2021-43535 |
| Alpine:v3.23 | thunderbird | 91.3.2-r0 | ALPINE-CVE-2021-43535 |
| Debian:12 | firefox-esr | 91.3.0esr-1 | DEBIAN-CVE-2021-43535 |
| Debian:13 | firefox-esr | 91.3.0esr-1 | DEBIAN-CVE-2021-43535 |
| Debian:14 | firefox-esr | 91.3.0esr-1 | DEBIAN-CVE-2021-43535 |
| Debian:12 | thunderbird | 1:91.3.0-1 | DEBIAN-CVE-2021-43535 |
| Debian:13 | thunderbird | 1:91.3.0-1 | DEBIAN-CVE-2021-43535 |
| Debian:14 | thunderbird | 1:91.3.0-1 | DEBIAN-CVE-2021-43535 |
| 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 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | unspecified – before 93 |
| Mozilla | Thunderbird | unspecified – before 91.3 |
| Mozilla | Firefox ESR | unspecified – before 91.3 |
References
- https://www.mozilla.org/security/advisories/mfsa2021-43/ x_refsource_MISC
- https://www.mozilla.org/security/advisories/mfsa2021-49/ x_refsource_MISC
- https://www.mozilla.org/security/advisories/mfsa2021-50/ x_refsource_MISC
- https://bugzilla.mozilla.org/show_bug.cgi?id=1667102 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