CVE-2023-44270
Data Injection vulnerability in postcss
What is CVE-2023-44270 About?
This issue in PostCSS before version 8.4.31 can lead to data injection in CSS comments, affecting linters that use PostCSS to parse external CSS. An attacker can craft malicious CSS that causes parts of a comment to be parsed as active CSS content. This can lead to unexpected behavior or security issues in applications relying on PostCSS for sanitization or linting.
Affected Software
Technical Details
The vulnerability in PostCSS arises from `\r` discrepancies during parsing, as demonstrated by the `@font-face{ font:(\r/*);}` example. An attacker can carefully construct CSS input where a CSS comment (`/* ... */`) contains specific character sequences (e.g., `\r`) that cause PostCSS to misinterpret parts of the comment. After PostCSS processes this input, the segments that were originally within a comment are erroneously included in the PostCSS output as active CSS nodes (e.g., rules or properties). This 'comment breakout' allows an attacker to inject CSS data that an application might assume was benign and commented out.
What is the Impact of CVE-2023-44270?
Successful exploitation may allow attackers to bypass security controls in linters, inject malicious CSS, or cause unexpected rendering in web applications, potentially leading to cross-site scripting (XSS) or defacement.
What is the Exploitability of CVE-2023-44270?
Exploitation of this vulnerability is of moderate complexity, requiring an understanding of PostCSS parsing and how character discrepancies are handled. Attackers must be able to supply untrusted external CSS to an application that uses PostCSS for parsing. There are no explicit authentication or privilege requirements beyond the ability to provide the CSS input. This is typically a remote vulnerability, as it targets web applications processing user-supplied styles. The primary risk factor is the deployment of linters or other processing tools that rely on PostCSS to correctly parse and sanitize untrusted CSS from external sources.
What are the Known Public Exploits?
| PoC Author | Link | Commentary |
|---|---|---|
| No known exploits | ||
What are the Available Fixes for CVE-2023-44270?
About the Fix from Resolved Security
The patch updates a regular expression in the tokenizer to also detect carriage return characters (\r) in the bad bracket detection logic, preventing malformed inputs from bypassing the parser's checks. This change fixes CVE-2023-44270 by ensuring that maliciously crafted inputs using carriage returns to obfuscate unclosed strings or comments are properly detected and rejected, mitigating a potential denial of service or injection attack.
Available Upgrade Options
- postcss
- <8.4.31 → Upgrade to 8.4.31
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Book a demoAdditional Resources
- https://github.com/postcss/postcss
- https://github.com/postcss/postcss/commit/58cc860b4c1707510c9cd1bc1fa30b423a9ad6c5
- https://github.com/github/advisory-database/issues/2820
- https://github.com/postcss/postcss/blob/main/lib/tokenize.js#L25
- https://github.com/postcss/postcss/blob/main/lib/tokenize.js#L25
- https://github.com/github/advisory-database/issues/2820
- https://github.com/postcss/postcss/commit/58cc860b4c1707510c9cd1bc1fa30b423a9ad6c5
- https://osv.dev/vulnerability/GHSA-7fh5-64p2-3v2j
- https://github.com/postcss/postcss/releases/tag/8.4.31
- https://github.com/postcss/postcss/releases/tag/8.4.31
What are Similar Vulnerabilities to CVE-2023-44270?
Similar Vulnerabilities: CVE-2022-34980 , CVE-2021-23381 , CVE-2020-7798 , CVE-2020-13936 , CVE-2020-14199
