CVE-2025-59042 — PyInstaller has local privilege escalation vulnerability
PyInstaller bundles a Python application and all its dependencies into a single package. Due to a special entry being appended to `sys.path` during the bootstrap process of a PyInstaller-frozen application, and due to the bootstrap script attempting to load an optional module for bytecode decryption while this entry is still present in `sys.path`, an application built with PyInstaller < 6.0.0 may be tricked by an unprivileged attacker into executing arbitrary python code when **all** of the following conditions are met. First, the application is built with PyInstaller < 6.0.0; both onedir and onefile mode are affected. Second, the optional bytecode encryption code feature was not enabled during the application build. Third, the attacker can create files/directories in the same directory where the executable is located. Fourth, the filesystem supports creation of files/directories that contain `?` in their name (i.e., non-Windows systems). Fifth, the attacker is able to determine the offset at which the PYZ archive is embedded in the executable. The attacker can create a directory (or a zip archive) next to the executable, with the name that matches the format used by PyInstaller's bootloader to transmit information about the location of PYZ archive to the bootstrap script. If this directory (or zip archive) contains a python module whose name matches the name used by the optional bytecode encryption feature, this module will be loaded and executed by the bootstrap script (in the absence of the real, built-in module that is available when the bytecode-encryption feature is enabled). This results in arbitrary code execution that requires no modification of the executable itself. If the executable is running with elevated privileges (for example, due to having the `setuid` bit set), the code in the injected module is also executed with the said elevated privileges, resulting in a local privilege escalation. PyInstaller 6.0.0 (f5adf291c8b832d5aff7632844f7e3ddf7ad4923) removed support for bytecode encryption; this effectively removes the described attack vector, due to the bootstrap script not attempting to load the optional module for bytecode-decryption anymore. PyInstaller 6.10.0 (cfd60b510f95f92cb81fc42735c399bb781a4739) reworked the bootstrap process to avoid (ab)using `sys.path` for transmitting location of the PYZ archive, which further eliminates the possibility of described injection procedure. If upgrading PyInstaller is not feasible, this issue can be worked around by ensuring proper permissions on directories containing security-sensitive executables (i.e., executables with `setuid` bit set) should mitigate the issue.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.1% (30-day exploitation probability)+0
- Technical severity (high)+6
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
- Pip Pyinstaller: fixed in version 6.0.0 — github.com (GitHub Security Advisories)
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Pyinstaller Pyinstaller, Pip Pyinstaller).
- Apply the fixed version or the patch documented under Remediation.
- Exploitation requires user interaction: tighten email/web filtering and warn affected users.
- Search available logs for exploit probes matching the vulnerability class (injection), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Pyinstaller | Pyinstaller | version < 6.0.0 | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Pip | Pyinstaller | < 6.0.0 | Vulnerable | GitHub Security Advisories |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 7.0 | CVSS 4.0 | High | — | — | security-advisories@github.com via NIST National Vulnerability Database |
| 7.0 | CVSS 4.0 | High | — | — | GitHub_M via CVE Program (cve.org) e CISA ADP |
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X (score shown at the top: security-advisories@github.com) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
- Look for parameters with command/query metacharacters and unexpected child processes of the service.
Timeline
What happened to this CVE, newest first.
- 2026
- Fix documented
- Affected products added · pip/pyinstaller
- Affected products added · pyinstaller/pyinstaller
- SSVC assessment updated
- Record published
- CVSS changed · 7.0
- Source status changed · → Deferred
- Record created in this database
- 2025
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 2× References added · Oct 19, 2026 – Oct 19, 2026
- 1× Official description updated · Oct 19, 2026 – Oct 19, 2026
References
4 on the record
Elsewhere on this site
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2025-59042 is "PyInstaller has local privilege escalation vulnerability", rated High. It affects Pyinstaller (Pyinstaller); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.0 describes technical severity. EPSS 0.13% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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