GHSA-gp7f-rwcx-9369
MEDIUMjsoup may not sanitize code injection XSS attempts if SafeList.preserveRelativeLinks is enabled
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
org.jsoup:jsoupReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
jsoup may incorrectly sanitize HTML including javascript: URL expressions, which could allow cross-site scripting (XSS) attacks when a reader subsequently clicks that link. If the non-default SafeList.preserveRelativeLinks option is enabled, HTML including javascript: URLs that have been crafted with control characters will not be sanitized. If the site that this HTML is published on does not set a Content Security Policy, an XSS attack is then possible.
Impact
Sites that accept input HTML from users and use jsoup to sanitize that HTML, may be vulnerable to cross-site scripting (XSS) attacks, if they have enabled SafeList.preserveRelativeLinks and do not set an appropriate Content Security Policy.
Patches
This issue is patched in jsoup 1.15.3.
Users should upgrade to this version. Additionally, as the unsanitized input may have been persisted, old content should be cleaned again using the updated version.
Workarounds
To remediate this issue without immediately upgrading:
- disable
SafeList.preserveRelativeLinks, which will rewrite input URLs as absolute URLs - ensure an appropriate Content Security Policy is defined. (This should be used regardless of upgrading, as a defence-in-depth best practice.)
Background and root cause
jsoup includes a Cleaner component, which is designed to sanitize input HTML against configurable safe-lists of acceptable tags, attributes, and attribute values.
This includes removing potentially malicious attributes such as <a href="javascript:...">, which may enable XSS attacks. It does this by validating URL attributes against allowed URL protocols (e.g. http, https).
However, an attacker may be able to bypass this check by embedding control characters into the href attribute value. This causes the Java URL class, which is used to resolve relative URLs to absolute URLs before checking the URL's protocol, to treat the URL as a relative URL. It is then resolved into an absolute URL with the configured base URI.
For example, java\tscript:... would resolve to https://example.com/java\tscript:....
By default, when using a safe-list that allows a tags, jsoup will rewrite any relative URLs (e.g. /foo/) to an absolute URL (e.g. https://example.com/foo/). Therefore, this attack attempt would be successfully mitigated. However, if the option SafeList.preserveRelativeLinks is enabled (which does not rewrite relative links to absolute), the input is left as-is.
While Java will treat a path like java\tscript: as a relative path, as it does not match the allowed characters of a URL spec, browsers may normalize out the control characters, and subsequently evaluate it as a javascript: spec inline expression. That disparity then leads to an XSS opportunity.
Sites defining a Content Security Policy that does not allow javascript expressions in link URLs will not be impacted, as the policy will prevent the script's execution.
For more information
If you have any questions or comments about this advisory:
- Open an issue in jsoup
- Email the author of jsoup at [email protected]
Credits
Thanks to Jens Häderer, who reported this issue, and contributed to its resolution.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.jsoup:jsoup | all versions | 1.15.3 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.jsoup:jsoup. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update org.jsoup:jsoup to 1.15.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-gp7f-rwcx-9369 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-gp7f-rwcx-9369 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-gp7f-rwcx-9369. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-gp7f-rwcx-9369 in your dependencies?
O3 detects GHSA-gp7f-rwcx-9369 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.