CVE-2021-38503

Description

The iframe sandbox rules were not correctly applied to XSLT stylesheets, allowing an iframe to bypass restrictions such as executing scripts or navigating the top-level frame. This vulnerability affects Firefox < 94, Thunderbird < 91.3, and Firefox ESR < 91.3.

Category

10.0
CVSS
Severity: Critical
CVSS 3.1 •
CVSS 2.0 •
EPSS 1.03% Top 25%
Vendor Advisory debian.org Vendor Advisory debian.org Vendor Advisory gentoo.org Vendor Advisory gentoo.org Vendor Advisory mozilla.org Vendor Advisory mozilla.org Vendor Advisory mozilla.org Vendor Advisory mozilla.org
Affected: Mozilla Firefox
Affected: Mozilla Thunderbird
Affected: Mozilla Firefox ESR
Published at:
Updated at:

References

Link Tags
https://www.mozilla.org/security/advisories/mfsa2021-49/ vendor advisory
https://www.mozilla.org/security/advisories/mfsa2021-50/ vendor advisory
https://www.mozilla.org/security/advisories/mfsa2021-48/ vendor advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1729517 vendor advisory issue tracking permissions required
https://www.debian.org/security/2021/dsa-5026 third party advisory vendor advisory
https://lists.debian.org/debian-lts-announce/2021/12/msg00030.html third party advisory mailing list
https://www.debian.org/security/2022/dsa-5034 third party advisory vendor advisory
https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html third party advisory mailing list
https://security.gentoo.org/glsa/202202-03 third party advisory vendor advisory
https://security.gentoo.org/glsa/202208-14 third party advisory vendor advisory

Frequently Asked Questions

What is the severity of CVE-2021-38503?
CVE-2021-38503 has been scored as a critical severity vulnerability.
How to fix CVE-2021-38503?
To fix CVE-2021-38503, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-38503 being actively exploited in the wild?
It is possible that CVE-2021-38503 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~1% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-38503?
CVE-2021-38503 affects Mozilla Firefox, Mozilla Thunderbird, Mozilla Firefox ESR.
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