CVE-2025-10155: Picklescan Bypass is Possible via File Extension Mismatch

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 0.8%, percentile 58: FIRST’s model estimates a 0.8% chance of exploitation activity in the next 30 days, higher than 58% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes picklescan (PyPI) <= 0.0.30, fixed in 0.0.31. Check your lockfile, including transitive dependencies.

What it is

An Improper Input Validation vulnerability in the scanning logic of mmaitre314 picklescan versions up to and including 0.0.30 allows a remote attacker to bypass pickle files security checks by supplying a standard pickle file with a PyTorch-related file extension. When the pickle file incorrectly considered safe is loaded, it can lead to the execution of malicious code.

From the GitHub advisory

Summary Picklescan can be bypassed, allowing the detection of malicious pickle files to fail, when a standard pickle file is given a PyTorch-related file extension (e.g., .bin). This occurs because the scanner prioritizes PyTorch file extension checks and errors out when parsing a standard pickle file with such an extension instead of falling back to standard pickle analysis. This vulnerability allows attackers to disguise malicious pickle payloads within files that would otherwise be scanned for pickle-based threats. Details The vulnerability stems from the logic in the scanbytes function within picklescan/scanner.py, specifically around line 463: https://github.com/mmaitre314/picklescan/blob/75e60f2c02f3f1a029362e6f334e1921392dcf60/src/picklescan/scanner.py#L463 The code first checks if the file extension (fileext) is in the pytorchfileextension list. If it is (e.g., .bin), the scanpytorch function is called. When a standard pickle file is encountered with a PyTorch extension, scanpytorch will likely fail. Critically, the code then returns an Error without attempting to analyze the file as a standard pickle using scanpicklebytes. This prevents the detection of malicious payloads within such files. PoC - Download a malicious pickle file with a standard .pkl extension: wget -O model.pkl - Scan the file with Picklescan (correct detection): /home/davfr/Tests/HF/dangerousmodel/model.pkl: dangerous import 'builtins exec' FOUND ----------- SCAN SUMMARY ----------- Scanned files: 1 Infected files: 1 Dangerous globals: 1

- Rename the file to use a PyTorch-related extension (e.g., .bin): cp model.pkl model.bin - Scan the renamed file with Picklescan:

Observed Result: Picklescan fails and reports an error related to PyTorch parsing but does not detect the malicious pickle content. Expected Result: Picklescan should recognize the file as a standard pickle format despite the .bin extension and scan it accordingly, identifying the malicious content. Impact Severity: High Affected Users: Any organization or…

Weakness type: CWE-20, CWE-693.

Product: picklescan (PyPI) · Assigned by: JFROG · Published: 2025-09-17

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: none
• Privileges required: none (no login)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation poc, automatable no, technical impact partial.
• FIRST EPSS (model of 2026-10-21): 0.85% probability of exploitation activity in the next 30 days; percentile 58.

Timeline

• 2025-09-10 — GitHub-reviewed advisory GHSA-jgw4-cr84-mqxg published (critical)
• 2025-09-17 — CVE record last updated
• 2025-09-17 — CVE record published by JFROG

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

1. Proof of Concept Instructions (GHSA) github.com

Vulnerability records

1. GitHub Advisory GHSA-jgw4-cr84-mqxg github.com
2. CVE.org record CVE-2025-10155 cve.org
3. NVD entry CVE-2025-10155 nvd.nist.gov

Other references from the CVE record and advisory

1. Vulnerable Code github.com
2. github.com github.com
3. github.com github.com

Critical PyPI advisories · Today’s Security Digest