Summary
RestrictedPython vulnerable to sandbox escape via string.Formatter field resolution
Workarounds
Do not expose the standard library string module or string.Formatter to restricted code.
If a custom import hook is used, deny imports of string or provide only a restricted wrapper that does not expose Formatter. If custom globals are supplied, ensure neither string.Formatter nor Formatter instances are available to restricted code.
Impact
RestrictedPython could allow a sandbox escape when a policy exposes the standard library string module, or otherwise exposes string.Formatter, to restricted code.
string.Formatter field resolution methods such as get_field can perform attribute and item traversal internally and return live object references. This can bypass RestrictedPython's normal attribute guards and may allow access to sensitive objects such as function globals, builtins, file access, or code execution primitives.
Users are impacted if they run untrusted code with RestrictedPython and expose string.Formatter, directly or indirectly, for example through a custom import policy or globals.
CVE-2026-76825 has a CVSS score of 8.4 (High). The vector is network-reachable, high privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (8.4); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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The problem has been patched by blocking access to string.Formatter and unsafe string.Formatter traversal methods in safer_getattr.
Users should upgrade to the patched release once available. Affected and patched version numbers should be filled in when the release is published.
Frequently Asked Questions
- What is CVE-2026-76825? CVE-2026-76825 is a high-severity security vulnerability in RestrictedPython (pip), affecting versions < 8.4. It is fixed in 8.4.
- How severe is CVE-2026-76825? CVE-2026-76825 has a CVSS score of 8.4 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of RestrictedPython are affected by CVE-2026-76825? RestrictedPython (pip) versions < 8.4 is affected.
- Is there a fix for CVE-2026-76825? Yes. CVE-2026-76825 is fixed in 8.4. Upgrade to this version or later.
- Is CVE-2026-76825 exploitable, and should I be worried? Whether CVE-2026-76825 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-76825 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-76825? Upgrade
RestrictedPythonto 8.4 or later.