GHSA-v92g-xgxw-vvmm is a high-severity (CVSS 7.5) vulnerability in mako. O3 Security confirms whether GHSA-v92g-xgxw-vvmm is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Mako: Path traversal via double-slash URI prefix in TemplateLookup
Real-World Exposure
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Description
Summary
TemplateLookup.get_template() is vulnerable to path traversal when a URI starts with // (e.g., //../../../secret.txt). The root cause is an inconsistency between two slash-stripping implementations:
Template.__init__strips one leading/usingif/sliceTemplateLookup.get_template()strips all leading/usingre.sub(r"^\/+", "")
When a URI like //../../../../etc/passwd is passed:
get_template()strips all/→../../../../etc/passwd→ file found viaposixpath.join(dir_, u)Template.__init__strips one/→/../../../../etc/passwd→normpath→/etc/passwd/etc/passwd.startswith(..) →False→ check bypassed
Impact
Arbitrary file read: any file readable by the process can be returned as rendered template content when an application passes untrusted input directly to TemplateLookup.get_template().
Note: this is exploitable at the library API level. HTTP-based exploitation is mitigated by Python's BaseHTTPRequestHandler which normalizes double-slash prefixes since CPython gh-87389. Applications using other HTTP servers that do not normalize paths may be affected.
Fix
Changed Template.__init__ to use lstrip("/") instead of stripping only a single leading slash, so both code paths handle leading slashes consistently.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | mako | all versions | 1.3.11 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mako. 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 mako to 1.3.11 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-v92g-xgxw-vvmm 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-v92g-xgxw-vvmm 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-v92g-xgxw-vvmm. 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-v92g-xgxw-vvmm in your dependencies?
O3 detects GHSA-v92g-xgxw-vvmm across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.