CVE-2015-0838
CRITICALCVE-2015-0838 is a critical-severity (CVSS 9.8) Buffer Overflow vulnerability in dulwich. O3 Security confirms whether CVE-2015-0838 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Dulwich Buffer Overflow when handling pack files
Real-World Exposure
dulwichReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Buffer overflow in the C implementation of the apply_delta function in _pack.c in Dulwich before 0.9.9 allows remote attackers to execute arbitrary code via a crafted pack file.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | dulwich | all versions | 0.9.9 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for dulwich. 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 dulwich to 0.9.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2015-0838 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 CVE-2015-0838 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 CVE-2015-0838. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2015-0838 in your dependencies?
O3 detects CVE-2015-0838 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.