RHSA-2021:3756 — Security Advisory
Red Hat Security Advisory: firefox security update
Severity
ImportantRed Hat Product Security
Products
Official CSAF product identity
Published · October 11, 2021
Updated · November 22, 2025
Topic
An update for firefox is now available for Red Hat Enterprise Linux 8.2 Extended Update Support.
Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.
Description
Mozilla Firefox is an open-source web browser, designed for standards compliance, performance, and portability.
This update upgrades Firefox to version 91.2.0 ESR.
Security Fix(es):
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Mozilla: Use-after-free in MessageTask (CVE-2021-38496)
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Mozilla: Memory safety bugs fixed in Firefox 93, Firefox ESR 78.15, and Firefox ESR 91.2 (CVE-2021-38500)
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Mozilla: Memory safety bugs fixed in Firefox 93 and Firefox ESR 91.2 (CVE-2021-38501)
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rust-crossbeam-deque: race condition may lead to double free (CVE-2021-32810)
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Mozilla: Validation message could have been overlaid on another origin (CVE-2021-38497)
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Mozilla: Use-after-free of nsLanguageAtomService object (CVE-2021-38498)
For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.