Vulnerability · Published Sep 16, 2026 · Assigned by GitHub_M

CVE-2026-76825RestrictedPython: Sandbox escape via string.Formatter field resolution

High 8.4

In plain English

A high-severity information exposure in RestrictedPython from zopefoundation. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 50% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.4High

Exploit odds (30 days)0.6%top 49.9% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

RestrictedPython is a tool that helps define a subset of the Python language for accepting program input in a trusted environment. Prior to 8.4, RestrictedPython could allow a sandbox escape when a custom import policy or globals exposed the standard library string module, the string.Formatter class, a Formatter instance, or a Formatter subclass to restricted code. The string.Formatter methods format, get_field, get_value, and vformat performed attribute and item traversal internally without passing through RestrictedPython's safer_getattr protections. Restricted code could use those live object references to reach function globals, builtins, file access, or code execution primitives, affecting confidentiality, integrity, and availability in the host environment. This issue is fixed in version 8.4.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	restrictedpython	no fix listed	DEBIAN-CVE-2026-76825
Debian:13	restrictedpython	no fix listed	DEBIAN-CVE-2026-76825
Debian:14	restrictedpython	8.4-1	DEBIAN-CVE-2026-76825
PyPI	restrictedpython	8.4	PYSEC-2026-4161
PyPI	restrictedpython	8.4	GHSA-hp3v-5vw7-fx9w
Ubuntu:26.04:LTS	restrictedpython	no fix listed	UBUNTU-CVE-2026-76825
Ubuntu:26.10	restrictedpython	no fix listed	UBUNTU-CVE-2026-76825

Affected products (as reported)

Vendor	Product	Versions
zopefoundation	RestrictedPython	< 8.4

Weakness: CWE-200, CWE-470, CWE-680, CWE-693 · Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:H

References

https://github.com/zopefoundation/RestrictedPython/security/advisories/GHSA-hp3v-5vw7-fx9w x_refsource_CONFIRM
https://github.com/zopefoundation/RestrictedPython/commit/3b47440070b91f8807c2b2998aca99e94783639a x_refsource_MISC
https://github.com/zopefoundation/RestrictedPython/releases/tag/8.4 x_refsource_MISC