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CVE Vulnerabilities

CVE-2021-4140

XML Injection (aka Blind XPath Injection)

Published: Dec 22, 2022 | Modified: Apr 16, 2025
CVSS 3.x
10
CRITICAL
Source:
NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CVSS 2.x
RedHat/V2
RedHat/V3
9.6 IMPORTANT
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Ubuntu
MEDIUM
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Additional information
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2021-4140
CWEhttps://cwe.mitre.org/data/definitions/91.html

It was possible to construct specific XSLT markup that would be able to bypass an iframe sandbox. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.

Weakness

The product does not properly neutralize special elements that are used in XML, allowing attackers to modify the syntax, content, or commands of the XML before it is processed by an end system.

Affected Software

NameVendorStart VersionEnd Version
FirefoxMozilla*96.0 (excluding)
Firefox_esrMozilla*91.5 (excluding)
ThunderbirdMozilla*91.5 (excluding)
Red Hat Enterprise Linux 7RedHatfirefox-0:91.5.0-1.el7_9*
Red Hat Enterprise Linux 7RedHatthunderbird-0:91.5.0-1.el7_9*
Red Hat Enterprise Linux 8RedHatthunderbird-0:91.5.0-1.el8_5*
Red Hat Enterprise Linux 8RedHatfirefox-0:91.5.0-1.el8_5*
Red Hat Enterprise Linux 8.1 Update Services for SAP SolutionsRedHatfirefox-0:91.5.0-1.el8_1*
Red Hat Enterprise Linux 8.1 Update Services for SAP SolutionsRedHatthunderbird-0:91.5.0-1.el8_1*
Red Hat Enterprise Linux 8.2 Extended Update SupportRedHatthunderbird-0:91.5.0-1.el8_2*
Red Hat Enterprise Linux 8.2 Extended Update SupportRedHatfirefox-0:91.5.0-1.el8_2*
Red Hat Enterprise Linux 8.4 Extended Update SupportRedHatfirefox-0:91.5.0-1.el8_4*
Red Hat Enterprise Linux 8.4 Extended Update SupportRedHatthunderbird-0:91.5.0-1.el8_4*
FirefoxUbuntubionic*
FirefoxUbuntudevel*
FirefoxUbuntufocal*
FirefoxUbuntuhirsute*
FirefoxUbuntuimpish*
FirefoxUbuntujammy*
FirefoxUbuntukinetic*
FirefoxUbuntulunar*
FirefoxUbuntumantic*
FirefoxUbuntunoble*
FirefoxUbuntutrusty*
FirefoxUbuntuupstream*
FirefoxUbuntuxenial*
Mozjs38Ubuntubionic*
Mozjs38Ubuntuesm-apps/bionic*
Mozjs38Ubuntuupstream*
Mozjs52Ubuntubionic*
Mozjs52Ubuntuesm-apps/focal*
Mozjs52Ubuntuesm-infra/bionic*
Mozjs52Ubuntufocal*
Mozjs52Ubuntuupstream*
Mozjs68Ubuntuesm-infra/focal*
Mozjs68Ubuntufocal*
Mozjs68Ubuntuupstream*
Mozjs78Ubuntuesm-apps/jammy*
Mozjs78Ubuntuhirsute*
Mozjs78Ubuntuimpish*
Mozjs78Ubuntujammy*
Mozjs78Ubuntukinetic*
Mozjs78Ubuntulunar*
Mozjs78Ubuntuupstream*
ThunderbirdUbuntubionic*
ThunderbirdUbuntudevel*
ThunderbirdUbuntufocal*
ThunderbirdUbuntuhirsute*
ThunderbirdUbuntuimpish*
ThunderbirdUbuntujammy*
ThunderbirdUbuntukinetic*
ThunderbirdUbuntulunar*
ThunderbirdUbuntumantic*
ThunderbirdUbuntunoble*
ThunderbirdUbuntutrusty*
ThunderbirdUbuntuupstream*
ThunderbirdUbuntuxenial*

Potential Mitigations

  • Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
  • When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
  • Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

References

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