CVE-2025-71343 picklescan - Arbitrary Code Execution via lib2to3.pgen2.pgen.ParserGenerator.make_label Detection Bypass
Attackers can bypass picklescan detection to execute arbitrary code via malicious pickle files exploiting lib2to3 internals.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2025-71343?
CVE-2025-71343 is a high-severity unsafe deserialization vulnerability in picklescan, published on 4 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
picklescan before 0.0.30 fails to detect malicious pickle files that exploit lib2to3.pgen2.pgen.ParserGenerator.make_label function in the reduce method. Attackers can craft malicious pickle files with embedded code that evades detection but executes arbitrary commands when pickle.load() is called.
Weakness: CWE-502
Which versions are affected by CVE-2025-71343?
2 open source packages ship an affected version, including picklescan.
| Package | Affected | Fixed in |
|---|---|---|
picklescan PyPI | All versions | 0.0.30 |
picklescan PyPI | All versions | 0.0.30 |
How do I fix CVE-2025-71343?
Upgrade picklescan to 0.0.30 or later.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2025-71343 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-71343 exists.
Sources
Also known as GHSA-8f67-79jr-8vpr, GHSA-p9w7-82w4-7q8m.