Security readout for executives and security teams
Plain-English summary
A researcher reported that the popular Python parsing library PLY 3.11 has an undocumented option that loads a pickle file without checking it, which could let an attacker run their own code if they can control that file. A third party has publicly disputed the finding, arguing the demonstration does not actually run attacker code. Real-world risk depends on whether your applications let outside input reach this rarely used developer feature.
Executive priority
Treat as a moderate, developer-hygiene issue rather than an emergency patch. Direct engineering to confirm whether PLY is in use and whether the `picklefile` option is ever exposed to untrusted input; escalate only if that condition is met or if the dispute is resolved against the library.
Technical view
CVE-2025-56005 describes an undocumented `picklefile` parameter in PLY's `yacc()` function (version 3.11 on PyPI) that is deserialized via `pickle.load()` without validation, mapping to CWE-502. Because pickle can invoke `__reduce__` during load, a controlled path could yield code execution. NVD lists CVSS 9.8 (AV:N/AC:L/PR:N/UI:N), but a third-party GitHub repository publicly disputes the PoC's ability to achieve arbitrary code execution.
Likely exposure
PLY is a widely embedded parsing library, but the vulnerable parameter is a developer-facing option normally set to a local file. Exposure is elevated only where an application accepts untrusted input as the `picklefile` path or ships attacker-writable pickle artifacts. Red Hat has an open tracker (RHBZ#2431308) and CSAF VEX record, but no fixed vendor version is cited in the bundle.
Exploitation context
Not listed in CISA KEV and no confirmed in-the-wild exploitation is cited. Public PoC repositories exist, and a rebuttal repo argues the PoC does not complete successful arbitrary code execution. Exploitation presumes an attacker can influence the `picklefile` argument or replace the referenced pickle file — a scenario that is uncommon outside insecure integrations.
Researcher notes
CWE-502 via `pickle.load` on an undocumented parameter is a plausible unsafe-deserialization sink, but CVSS 9.8 assumes network-reachable, unauthenticated triggering that is not evident from the sources. The `tom025/ply_exploit_rejection` repo and its issue thread challenge the PoC. No vendor patch, no fixed version, and no KEV listing are cited; treat scoring as provisional until dispute status settles.
Mitigation direction
- Inventory Python projects that import `ply.yacc` and confirm whether `picklefile` is ever set.
- Never pass untrusted or attacker-controlled paths to the `picklefile` parameter of `yacc()`.
- Restrict filesystem permissions on any pickle artifacts consumed by PLY-based parsers.
- Track Red Hat CVE-2025-56005 and RHBZ#2431308 for a vendor-recommended patched build.
- Consider alternative parser generators or pin PLY away from 3.11 pending disposition of the dispute.
Validation and detection
- Grep dependencies for `ply==3.11` or PLY as a transitive dependency in `requirements.txt` and lockfiles.
- Search source for calls to `yacc.yacc(` and inspect for a `picklefile=` keyword argument.
- Confirm whether any code path lets external input reach that argument or the referenced file.
- Review Red Hat's CSAF VEX record for affected/unaffected component status.
- Monitor the CVE record and NVD for a resolution of the third-party dispute.
Public sources used
- CVE Program record — CVE-2025-56005
- CVE List V5 JSON
- Reporter PoC — Undocumented-RCE-in-PLY
- Reporter PoC — Undocumument_RCE_PLY-yacc-CVE-2025-56005
- Third-party rejection analysis — ply_exploit_rejection
- Rejection discussion thread
- Red Hat security advisory
- Red Hat Bugzilla RHBZ#2431308
- Red Hat CSAF VEX record
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-502: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2025-56005 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9redhat-SADPVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- ADP timelineredhat-SADP
Made public.
- CVE publishedCVE Program
The CVE record was published.
- ADP timelineredhat-SADP
Reported to Red Hat.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2026-01-20T19:00:55.111Z: Reported to Red Hat.
- 2026-01-20T00:00:00.000Z: Made public.
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/bohmiiidd/Undocumented-RCE-in-PLYCVE reference, mitre
- https://github.com/tom025/ply_exploit_rejectionCVE reference, mitre
- https://github.com/bohmiiidd/Undocumument_RCE_PLY-yacc-CVE-2025-56005CVE reference, mitre
- https://github.com/tom025/ply_exploit_rejection/issues/1CVE reference, mitre
- https://access.redhat.com/security/cve/CVE-2025-56005CVE reference, redhat-SADP · vdb-entry, x_refsource_REDHAT
- RHBZ#2431308CVE reference, redhat-SADP · issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-56005.jsonCVE reference, redhat-SADP · x_sadp-csaf-vex
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Deserialization of Untrusted Data
Deserialization of Untrusted Data represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.