# CVE-2026-70463: rsync 3.1.0 < 3.5.0 Authorization Bypass via auth users Directive Parsing

> An authenticated user can bypass access restrictions on rsync modules if the auth users directive contains group names with spaces, allowing unauthorized access to restricted data.

- **Severity:** High 8.6 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 13 Aug 2026
- **Updated:** 14 Aug 2026
- **Also known as:** ALPINE-CVE-2026-70463, AZL-95801, BELL-CVE-2026-70463, DEBIAN-CVE-2026-70463, ECHO-f2d9-9a60-877f, GHSA-pfj8-79vq-xgvr, ROOT-OS-DEBIAN-11-CVE-2026-70463, UBUNTU-CVE-2026-70463

## What is CVE-2026-70463?

CVE-2026-70463 is a high-severity authentication bypass vulnerability in RsyncProject rsync, published on 13 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

rsync 3.1.0 before 3.5.0 contains an authorization bypass in auth users directive parsing. The auth users parser uses comma-only tokenization when splitting the user list, which fails to correctly handle entries of the form @Group Name where the group name contains a space. The space within the group name causes the parser to split the entry at the space boundary, discarding the deny rule associated with the group. An authenticated user whose username or group membership would be denied by an @Group Name auth users entry can connect to a restricted module because the deny rule is silently discarded during parsing.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2026-70463?

It affects 1 product.


Products: Samba Rsync.

## How do I fix CVE-2026-70463?

Upgrade to a fixed version.

## Is CVE-2026-70463 being exploited?

There is no known exploitation of CVE-2026-70463 in the wild and no public exploit code.

Public exploit code:

- Testing CVE-2026-70463 by Fyyre (github_poc): https://github.com/Fyyre/CVE-2026-70463

## Other vulnerabilities in RsyncProject rsync

- [CVE-2017-15994](https://insights.sbomify.com/CVE-2017-15994/): Security feature bypass in n/a (critical 9.8)
- [CVE-2026-53791](https://insights.sbomify.com/CVE-2026-53791/): rsync < 3.5.0 Daemon IP Spoofing via PROXY Protocol Header (critical 9.1)
- [CVE-2026-70461](https://insights.sbomify.com/CVE-2026-70461/): rsync 3.2.5 < 3.5.0 Heap Out-of-Bounds Write via files-from Entry (high 8.8)
- [CVE-2026-70455](https://insights.sbomify.com/CVE-2026-70455/): rsync 3.4.2 < 3.5.0 DoS via --zt Zstandard Compression Thread Exhaustion (high 8.7)
- [CVE-2026-53803](https://insights.sbomify.com/CVE-2026-53803/): rsync < 3.5.0 Symlink Following Arbitrary File Overwrite (high 8.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-70463 and fix it if it is affected.

What it is: CVE-2026-70463 is a high-severity authentication bypass vulnerability in RsyncProject rsync, published on 13 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-70463 in the wild and no public exploit code.

Affected product: RsyncProject rsync. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-70463/ (Markdown: https://insights.sbomify.com/CVE-2026-70463/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-70463
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-70463
- OSV: https://osv.dev/vulnerability/CVE-2026-70463

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-70463/
Summaries are generated and may contain mistakes; the official description above is the record.