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AUSCERT External Security Bulletin Redistribution
ESB-2021.3000
MFSA 2021-38 Security Vulnerabilities fixed in Firefox and Firefox ESR
8 September 2021
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AusCERT Security Bulletin Summary
---------------------------------
Product: Firefox
Firefox ESR
Publisher: Mozilla
Operating System: Windows
UNIX variants (UNIX, Linux, OSX)
Android
Impact/Access: Execute Arbitrary Code/Commands -- Remote with User Interaction
Denial of Service -- Remote with User Interaction
Provide Misleading Information -- Remote with User Interaction
Reduced Security -- Remote with User Interaction
Resolution: Patch/Upgrade
CVE Names: CVE-2021-38495 CVE-2021-38494 CVE-2021-38493
CVE-2021-38492 CVE-2021-38491 CVE-2021-29993
Reference: ESB-2021.2999
Original Bulletin:
https://www.mozilla.org/en-US/security/advisories/mfsa2021-38/
https://www.mozilla.org/en-US/security/advisories/mfsa2021-39/
https://www.mozilla.org/en-US/security/advisories/mfsa2021-40/
Comment: This bulletin contains three (3) Mozilla security advisories.
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Mozilla Foundation Security Advisory 2021-38
Security Vulnerabilities fixed in Firefox 92
Announced: September 7, 2021
Impact: high
Products: Firefox
Fixed in: Firefox 92
# CVE-2021-29993: Handling custom intents could lead to crashes and UI spoofs
Reporter: Amy Burnett working with Include Security
Impact: high
Description
Firefox for Android allowed navigations through the intent:// protocol, which
could be used to cause crashes and UI spoofs.
This bug only affects Firefox for Android. Other operating systems are
unaffected.
References
o Bug 1712242, 1708767, 1712240, 1708544, 1729259
# CVE-2021-38491: Mixed-Content-Blocking was unable to check opaque origins
Reporter: Jonathan Kingston
Impact: moderate
Description
Mixed-content checks were unable to analyze opaque origins which led to some
mixed content being loaded.
References
o Bug 1551886
# CVE-2021-38492: Navigating to `mk:` URL scheme could load Internet Explorer
Reporter: James Lee
Impact: moderate
Description
When delegating navigations to the operating system, Firefox would accept the
mk scheme which might allow attackers to launch pages and execute scripts in
Internet Explorer in unprivileged mode.
This bug only affects Firefox for Windows. Other operating systems are
unaffected.
References
o Bug 1721107
# CVE-2021-38493: Memory safety bugs fixed in Firefox 92, Firefox ESR 78.14 and
Firefox ESR 91.1
Reporter: Mozilla developers and community
Impact: high
Description
Mozilla developers Gabriele Svelto and Tyson Smith reported memory safety bugs
present in Firefox 91 and Firefox ESR 78.13. Some of these bugs showed evidence
of memory corruption and we presume that with enough effort some of these could
have been exploited to run arbitrary code.
References
o Memory safety bugs fixed in Firefox 92, Firefox ESR 78.14 and Firefox ESR
91.1
# CVE-2021-38494: Memory safety bugs fixed in Firefox 92
Reporter: Mozilla developers and community
Impact: high
Description
Mozilla developers Christian Holler and Lars T Hansen reported memory safety
bugs present in Firefox 91. Some of these bugs showed evidence of memory
corruption and we presume that with enough effort some of these could have been
exploited to run arbitrary code.
References
o Memory safety bugs fixed in Firefox 92
- -------------------------------------------------------------------------------
Mozilla Foundation Security Advisory 2021-39
Security Vulnerabilities fixed in Firefox ESR 78.14
Announced: September 7, 2021
Impact: moderate
Products: Firefox ESR
Fixed in: Firefox ESR 78.14
# CVE-2021-38492: Navigating to `mk:` URL scheme could load Internet Explorer
Reporter: James Lee
Impact: moderate
Description
When delegating navigations to the operating system, Firefox would accept the
mk scheme which might allow attackers to launch pages and execute scripts in
Internet Explorer in unprivileged mode.
This bug only affects Firefox for Windows. Other operating systems are
unaffected.
References
o Bug 1721107
# CVE-2021-38493: Memory safety bugs fixed in Firefox 92, Firefox ESR 78.14 and
Firefox ESR 91.1
Reporter: Mozilla developers and community
Impact: high
Description
Mozilla developers Tyson Smith and Gabriele Svelto reported memory safety bugs
present in Firefox 91 and Firefox ESR 78.13. Some of these bugs showed evidence
of memory corruption and we presume that with enough effort some of these could
have been exploited to run arbitrary code.
References
o Memory safety bugs fixed in Firefox 92, Firefox ESR 78.14 and Firefox ESR
91.1
- -------------------------------------------------------------------------------
Mozilla Foundation Security Advisory 2021-40
Security Vulnerabilities fixed in Firefox ESR 91.1
Announced: September 7, 2021
Impact: low
Products: Firefox ESR
Fixed in: Firefox ESR 91.1
# CVE-2021-38492: Navigating to `mk:` URL scheme could load Internet Explorer
Reporter: James Lee
Impact: moderate
Description
When delegating navigations to the operating system, Firefox would accept the
mk scheme which might allow attackers to launch pages and execute scripts in
Internet Explorer in unprivileged mode.
This bug only affects Firefox for Windows. Other operating systems are
unaffected.
References
o Bug 1721107
# CVE-2021-38495: Memory safety bugs fixed in Firefox 92 and Firefox ESR 91.1
Reporter: Mozilla developers and community
Impact: high
Description
Mozilla developers Tyson Smith, Christian Holler, and Gabriele Svelto reported
memory safety bugs present in Firefox 91 and Firefox ESR 91.0. Some of these
bugs showed evidence of memory corruption and we presume that with enough
effort some of these could have been exploited to run arbitrary code.
References
o Memory safety bugs fixed in Firefox 92 and Firefox ESR 91.1
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