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.

The remote Fedora 44 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-1594a9755b advisory.

    Remove unsafe dead code (CVE-2025-56005) from the bundled ply

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Fedora 43 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-85a7950dd4 advisory.

    Fix jit backend for ppc64le and s390x

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Fedora 44 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-8199b7452a advisory.

    Fix jit backend for ppc64le and s390x

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Fedora 43 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-516db080b7 advisory.

    Security fix for CVE-2025-56005

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Fedora 44 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-c081ac890b advisory.

    Security fix for CVE-2025-56005

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Fedora 43 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-98502d7938 advisory.

    Security fix for CVE-2025-56005 for the bundled ply within the bundled pycparser

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Fedora 43 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-6c4a7cd1b1 advisory.

    Fix jit backend for ppc64le and s390x

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Fedora 44 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-55dd4da86b advisory.

    Security fix for CVE-2025-56005 for the bundled ply within the bundled pycparser

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Fedora 44 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-496bf1e0dd advisory.

    Fix jit backend for ppc64le and s390x

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Fedora 45 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-47a943ac72 advisory.

    Automatic update for python-ply-3.11-33.fc45.

    ##### **Changelog**

    ```
    * Wed Mar 25 2026 Charalampos Stratakis <cstratak@redhat.com> - 3.11-33
    - Security fix for CVE-2025-56005
    - Fixes: rhbz#2437981

    ```

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Fedora 45 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-06635fd623 advisory.

    Automatic update for pypy3.10-7.3.19-11.3.10.fc45.

    ##### **Changelog**

    ```
    * Thu Mar 19 2026 Charalampos Stratakis <cstratak@redhat.com> - 7.3.19-11
    - Security fix for CVE-2025-56005 for the bundled ply within the bundled       pycparser
    - Fixes: rhbz#2431977

    ```

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Fedora 45 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-7585365ba3 advisory.

    Automatic update for pypy-7.3.21-3.fc45.

    ##### **Changelog**

    ```
    * Thu Mar 19 2026 Charalampos Stratakis <cstratak@redhat.com> - 7.3.21-2
    - Security fix for CVE-2025-56005 for the bundled ply within the bundled       pycparser
    - Fixes: rhbz#2431976
    * Thu Mar 19 2026 Charalampos Stratakis <cstratak@redhat.com> - 7.3.21-1
    - Update to 7.3.21
    - Fixes: rhbz#2447284

    ```

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Fedora 45 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2026-ab51ea3744 advisory.

    Automatic update for pypy3.11-7.3.21-3.3.11.fc45.

    ##### **Changelog**

    ```
    * Thu Mar 19 2026 Charalampos Stratakis <cstratak@redhat.com> - 7.3.21-2
    - Fix CVE-2025-56005 via removing no-longer used bundled ply
    - Fixes: rhbz#2431978
    * Thu Mar 19 2026 Charalampos Stratakis <cstratak@redhat.com> - 7.3.21-1
    - Update to 7.3.21
    - Fixes: rhbz#2447285

    ```

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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. (CVE-2025-56005)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Severity
304259	Fedora 44 : python-pycparser (2026-1594a9755b)	Nessus	Fedora Local Security Checks	critical
304257	Fedora 43 : pypy3.11 (2026-85a7950dd4)	Nessus	Fedora Local Security Checks	critical
304250	Fedora 44 : pypy3.11 (2026-8199b7452a)	Nessus	Fedora Local Security Checks	critical
304202	Fedora 43 : python-ply (2026-516db080b7)	Nessus	Fedora Local Security Checks	critical
304197	Fedora 44 : python-ply (2026-c081ac890b)	Nessus	Fedora Local Security Checks	critical
304194	Fedora 43 : pypy3.10 (2026-98502d7938)	Nessus	Fedora Local Security Checks	critical
304186	Fedora 43 : pypy (2026-6c4a7cd1b1)	Nessus	Fedora Local Security Checks	critical
304181	Fedora 44 : pypy3.10 (2026-55dd4da86b)	Nessus	Fedora Local Security Checks	critical
304180	Fedora 44 : pypy (2026-496bf1e0dd)	Nessus	Fedora Local Security Checks	critical
303919	Fedora 45 : python-ply (2026-47a943ac72)	Nessus	Fedora Local Security Checks	critical
303206	Fedora 45 : pypy3.10 (2026-06635fd623)	Nessus	Fedora Local Security Checks	critical
303205	Fedora 45 : pypy (2026-7585365ba3)	Nessus	Fedora Local Security Checks	critical
303204	Fedora 45 : pypy3.11 (2026-ab51ea3744)	Nessus	Fedora Local Security Checks	critical
294837	Linux Distros Unpatched Vulnerability : CVE-2025-56005	Nessus	Misc.	critical

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CVE-2025-56005

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