How severe is CVE-2025-56005?

CVE-2025-56005 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2025-56005 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 17% (97th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-56005?

CVE-2025-56005 affects Dabeaz Ply. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-56005?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2025-56005 have an EU (EUVD) identifier?

Yes. CVE-2025-56005 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-3342.

When was CVE-2025-56005 published?

CVE-2025-56005 was published on 2026-01-20 and last updated on 2026-06-30.

CVE-2025-56005

CVE-2025-56005 is a critical-severity vulnerability in Dabeaz Ply with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 17% places it in the 97th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-502.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 17% (97th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-3342
Weakness: CWE-502
Affected product: Dabeaz Ply
Published: 2026-01-20
Last modified: 2026-06-30

Description

An undocumented and unsafe feature in the PLY (Python Lex-Yacc) library 3.11 allows Remote Code Execution (RCE) via the `picklefile` parameter in the `yacc()` function. This parameter accepts a `.pkl` file that is deserialized with `pickle.load()` without validation. Because `pickle` allows execution of embedded code via `__reduce__()`, an attacker can achieve code execution by passing a malicious pickle file. The parameter is not mentioned in official documentation or the GitHub repository, yet it is active in the PyPI version. This introduces a stealthy backdoor and persistence risk. NOTE: A third-party states that this vulnerability should be rejected because the proof of concept does not demonstrate arbitrary code execution and fails to complete successfully.

Frequently asked questions

What is CVE-2025-56005?: An undocumented and unsafe feature in the PLY (Python Lex-Yacc) library 3.11 allows Remote Code Execution (RCE) via the `picklefile` parameter in the `yacc()` function. This parameter accepts a `.pkl` file that is deserialized with `pickle.load()` without validation. Because `pickle` allows execution of embedded code via `__reduce__()`, an attacker can achieve code execution by passing a malicious pickle file. The parameter is not mentioned in official documentation or the GitHub repository, yet it is active in the PyPI version. This introduces a stealthy backdoor and persistence risk. NOTE: A third-party states that this vulnerability should be rejected because the proof of concept does not demonstrate arbitrary code execution and fails to complete successfully.
How severe is CVE-2025-56005?: CVE-2025-56005 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2025-56005 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 17% (97th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-56005?: CVE-2025-56005 affects Dabeaz Ply. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-56005?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2025-56005 have an EU (EUVD) identifier?: Yes. CVE-2025-56005 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-3342.
When was CVE-2025-56005 published?: CVE-2025-56005 was published on 2026-01-20 and last updated on 2026-06-30.

References

Affected products (1)

cpe:2.3:a:dabeaz:ply:3.11:*:*:*:*:*:*:*

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