GHSA-8rfp-98v4-mmr6
NONEGHSA-8rfp-98v4-mmr6 is a none-severity (CVSS 0) vulnerability in bleach. O3 Security confirms whether GHSA-8rfp-98v4-mmr6 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Bleach: URI sanitization allows disallowed URI schemes with Unicode > U+00A0 in output
Blast Radius
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Description
Impact
A possible XSS bypass affects users calling bleach.clean with all of:
ain the allowed tagshrefin allowed attributes
The bleach.clean sanitizer outputs URIs containing disallowed scheme patterns that it should be stripping. However, because the inserted Unicode characters make the scheme invalid per RFC 3986, modern browsers do not execute these as javascript: URIs. The practical security impact is limited to:
- Bleach's output contains URI values that violate the caller's protocol allowlist, breaking the sanitizer's contract.
- If a downstream system performs its own Unicode normalization on bleach's output (stripping invisible characters before rendering), the javascript: scheme could become valid. This is a non-standard processing chain but represents a theoretical secondary risk.
This is not a direct XSS vulnerability.
Python code example from reporter with Bleach v6.3.0 and Python 3.13:
import bleach
payload1 = '<a href="javascript\u200b:alert(document.cookie)">Click me</a>'
result1 = bleach.clean(payload1)
print(f"(ZWSP): {repr(result1)}")
Output:
(ZWSP): '<a href="javascript\u200b:alert(document.cookie)">Click me</a>'
Patches
Users should upgrade to Bleach 6.4.0.
Workarounds
Pre-process content removing non-ASCII characters from URI schemes before sanitizing with bleach.clean.
A strong Content-Security-Policy without unsafe-inline and unsafe-eval script-srcs will also help mitigate the risk.
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2023812
- RFC 3986, Section 3.1 (URI Scheme syntax): scheme characters are restricted to ALPHA *( ALPHA / DIGIT / "+" / "-" / "." )
Reported by
Reported by codeant from CodeAnt AI.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | bleach | all versions | 6.4.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for bleach. 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 bleach to 6.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8rfp-98v4-mmr6 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-8rfp-98v4-mmr6 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-8rfp-98v4-mmr6. 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-8rfp-98v4-mmr6 in your dependencies?
O3 detects GHSA-8rfp-98v4-mmr6 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.