GHSA-5fg8-2547-mr8q CVE-2021-32796
Misinterpretation of malicious XML input
- Severity
- 6.5 / 10
- Medium · CVSS 3.1
- Exploit chance (EPSS)
- 1.36%
- Chance of exploitation in the next 30 days. Higher than 71.69% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-116 Improper Encoding or Escaping of Output
- Fix
0.7.0- Upgrade @xmldom/xmldom to this version or later
Description
Impact
xmldom versions 0.6.0 and older do not correctly escape special characters when serializing elements removed from their ancestor. This may lead to unexpected syntactic changes during XML processing in some downstream applications.
Patches
Update to one of the fixed versions of @xmldom/xmldom (>=0.7.0)
See issue #271 for the status of publishing xmldom to npm or join #270 for Q&A/discussion until it's resolved.
Workarounds
Downstream applications can validate the input and reject the maliciously crafted documents.
References
Similar to this one reported on the Go standard library:
- https://mattermost.com/blog/coordinated-disclosure-go-xml-vulnerabilities/
- https://mattermost.com/blog/securing-xml-implementations-across-the-web/
For more information
If you have any questions or comments about this advisory:
- Open an issue in
xmldom/xmldom - Email us: send an email to all addresses that are shown by
npm owner ls @xmldom/xmldom
Affected versions
npm
| Package | Vulnerable | Fixed in |
|---|---|---|
| @xmldom/xmldom | < 0.7.0 |
0.7.0 |
| xmldom | <= 0.6.0 |
No fix yet |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
@xmldom/xmldom npm → 0.7.0
- npm
npm install @xmldom/xmldom@0.7.0- yarn
yarn add @xmldom/xmldom@0.7.0- pnpm
pnpm add @xmldom/xmldom@0.7.0
Severity breakdown
CVSS 3.1 6.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
Weakness
CWE-116: Improper Encoding or Escaping of Output
The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved.
How to prevent it
- Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using the ESAPI Encoding control [REF-45] or a similar tool, library, or framework. These will help the programmer encode outputs in a manner less prone to error. Alternately, use built-in functions, but consider using wrappers in case those functions are discovered to have a vulnerability.
- Architecture and Design: If available, use structured mechanisms that automatically enforce the separation between data and code. These mechanisms may be able to provide the relevant quoting, encoding, and validation automatically, instead of relying on the developer to provide this capability at every point where output is generated. For example, stored procedures can enforce database query structure and reduce the likelihood of SQL injection.
- Architecture and Design, Implementation: Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages. Study all expected communication protocols and data representations to determine the required encoding strategies.
- Architecture and Design: In some cases, input validation may be an important strategy when output encoding is not a complete solution. For example, you may be providing the same output that will be processed by multiple consumers that use different encodings or representations. In other cases, you may be required to allow user-supplied input to contain control information, such as limited HTML tags that support formatting in a wiki or bulletin board. When this type of requirement must be met, use an extremely strict allowlist to limit which control sequences can be used. Verify that the resulting syntactic structure is what you expect. Use your normal encoding methods for the remainder of the input.
- Architecture and Design: Use input validation as a defense-in-depth measure to reduce the likelihood of output encoding errors (see CWE-20).
- Requirements: Fully specify which encodings are required by components that will be communicating with each other.
- Implementation: When exchanging data between components, ensure that both components are using the same character encoding. Ensure that the proper encoding is applied at each interface. Explicitly set the encoding you are using whenever the protocol allows you to do so.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-x4fp-j954-r2f4 xmldom: End-tag Whitespace-Trim Regex ReDoS — quadratic backtracking in the 0.8.x end-tag parser | High | Also affects @xmldom/xmldom |
| GHSA-vr34-hp96-76pp xmldom: requireWellFormed DocType publicId/systemId validation is bypassable via an embedded line terminator | High | Also affects @xmldom/xmldom |
| GHSA-jxjr-3g7g-3944 xmldom: requireWellFormed element/attribute name validation is bypassable via an embedded line terminator | High | Also affects @xmldom/xmldom |
| GHSA-c7q8-3ch8-vqpv xmldom: Processing Instruction Target Injection Bypasses requireWellFormed | High | Also affects xmldom |
| GHSA-965w-775f-mr7g xmldom: Quadratic-memory consumption | High | Also affects xmldom |
| GHSA-93r5-fhx6-vmg9 xmldom: Quadratic-time parsing via the malformed-input recovery path — `parseElementStartPart` re-scan and `normalize()` adjacent-text merge | High | Also affects xmldom |
| GHSA-8344-3jmq-59r6 xmldom: Quadratic-time attribute deduplication | High | Also affects xmldom |
| GHSA-6mj3-qw4j-hgrw xmldom: HTML raw-text closing-tag case mismatch causes output amplification | High | Also affects @xmldom/xmldom |
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