high CVSS 7.5 EPSS 0.41%

CVE-2026-59939·Python vulnerability

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.

Severity
high
Software
Python
Fixed in
0.32.0
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at 0.41% — higher than 34% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Read the two together. CVE-2026-59939 scores 7.5 on CVSS, so a successful attack would be serious — but at 0.41%, almost nobody is currently attempting it. That is a different situation from a flaw under mass exploitation, and it is usually the difference between patching on your next maintenance window and patching tonight.

Affected versions

Until: 0.32.0

Fixed in: 0.32.0

How to fix this CVE

Update httplib2 to version 0.32.0 or later to resolve a decompression denial-of-service vulnerability in Python's HTTP client library. The vulnerability allows malicious HTTP servers to send compressed payloads that expand to excessive sizes, consuming unbounded memory and crashing client applications. Ensure all systems running httplib2 are patched immediately, particularly those making outbound HTTP connections to untrusted or internet-facing services.

sudo dnf update -y python3-httplib2 || sudo pip3 install --upgrade httplib2>=0.32.0

Defensia detects this vulnerability

How to check if you are affected

  1. Check installed httplib2 version with: python3 -c "import httplib2; print(httplib2.__version__)"
  2. Identify applications using httplib2 by searching for import statements: grep -r "import httplib2" /opt /srv /home --include="*.py" 2>/dev/null
  3. Monitor process memory usage and system logs for OOM-killer events: journalctl -u <service> | grep -i oom || dmesg | grep -i oom
  4. Verify patch installation by confirming httplib2 version >= 0.32.0: pip3 show httplib2 | grep Version

FAQ

What is CVE-2026-59939?

CVE-2026-59939 is a denial-of-service vulnerability in httplib2 where the library fails to limit decompression of gzip or deflate-encoded HTTP response bodies, allowing attackers to send small compressed payloads that decompress to arbitrarily large sizes and exhaust the client's memory.

Is CVE-2026-59939 being actively exploited?

No, there are currently no known active exploits or public proof-of-concept code for CVE-2026-59939, and it is not listed in the CISA Known Exploited Vulnerabilities catalog.

What versions of Python are affected by CVE-2026-59939?

All versions of httplib2 prior to 0.32.0 are vulnerable. The vulnerability affects any Python application using httplib2 for HTTP requests, regardless of the Python version installed.

How do I check if my server is vulnerable to CVE-2026-59939?

Run: python3 -c "import httplib2; print(httplib2.__version__)" and compare the version against 0.32.0. If the version is lower, your system is vulnerable.

Does Defensia detect CVE-2026-59939?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If httplib2 is installed on a monitored server, CVE-2026-59939 will appear in your dashboard with remediation steps.

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References

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