GHSA-43cp-6p3q-2pc4 — medium GitHub Advisory (CVE-2023-44390) in nuget/HtmlSanitizer

Description

Impact

The vulnerability occurs in configurations where foreign content is allowed, i.e. either svg or math are in the list of allowed elements.
Specifically, the requirements for the vulnerability are:

Allowing one foreign element: svg, or math
Comments or one raw text element: iframe, noembed, xmp, title, noframes, style or noscript

Configurations that meet the above requirements plus the following are vulnerable to an additional vulnerability:

Any HTML integration element: title, desc, mi, mo, mn, ms, mtext, annotation-xml.

In case an application sanitizes user input with a vulnerable configuration, an attacker could
bypass the sanitization and inject arbitrary HTML, including JavaScript code.

Note that in the default configuration the vulnerability is not present.

Patches

The vulnerability has been fixed in versions 8.0.723 and 8.1.722-beta (preview version).

Workarounds

Disallow foreign elements svg and math. This is the case in the default configuration, which is therefore not affected by the vulnerability.

Basic information

Type: reviewed
Severity: medium
Advisory on GitHub: Open advisory ↗
Repository advisory: Open repository advisory ↗
Source code: Browse source ↗
Published (advisory): 2023-10-04 18:52:35 UTC
Updated: 2023-11-09 05:01:55 UTC
GitHub reviewed: 2023-10-04 18:52:35 UTC
NVD published: 2023-10-05

Score	Percentile
0.16%	37.46%

CVSS Scores

Base score	Version	Severity	Vector
6.1	3.1	—	`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:R) A real person has to do something—click, install, enable—otherwise it doesn’t land. Scope (S:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. Confidentiality (C:L) Some sensitive info could get out, but not a total data dump. Integrity (I:L) Attackers could change some data, but it’s limited—not everything goes. Availability (A:N) Service keeps running; no real outage angle.

Identifiers

Type	Value
GHSA	GHSA-43cp-6p3q-2pc4 ↗
CVE	CVE-2023-44390 ↗

CWEs

CWE id	Name
CWE-79	Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Credits

Yaniv-git (finder)

Affected packages (2)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem	Package	Vulnerable range	First patched	Vulnerable functions
nuget	HtmlSanitizer	< 8.0.723	8.0.723	—
nuget	HtmlSanitizer	>= 8.1.0-beta, < 8.1.722-beta	8.1.722-beta	—

HtmlSanitizer vulnerable to Cross-site Scripting in Foreign Content