CVE-2026-59939 is a high-severity (CVSS 7.5) CWE-409 vulnerability in httplib2. O3 Security confirms whether CVE-2026-59939 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
httplib2: Decompression Bomb Denial of Service via Unbounded gzip/deflate Response Handling
Real-World Exposure
httplib2Real-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
httplib2 is a comprehensive HTTP client library for Python. Prior to 0.32.0, httplib2 performs unbounded decompression of HTTP response bodies encoded with Content-Encoding: gzip or deflate in _decompressContent in httplib2/init.py, allowing a malicious or compromised HTTP server to return a small compressed payload that expands to an arbitrarily large size in memory and causes MemoryError or OOM-kill in the client process. This issue is fixed in version 0.32.0.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | httplib2 | all versions | 0.32.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for httplib2. 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 httplib2 to 0.32.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-59939 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-2026-59939 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-2026-59939. 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-2026-59939 in your dependencies?
O3 detects CVE-2026-59939 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.