CVE-2026-44509: Auth Bypass (CVSS 6.3)

Description

Rsync is a file-copying tool that uses a delta-transfer algorithm to synchronize remote and local files. In versions prior to 3.4.3, previous bug fixes for symlink races in open() calls missed races in other path based system calls like chmod() and chown(). For rsync daemons with "use chroot = no" this allows an attacker with local filesystem access to change permissions, ownership or timestamp on a file outside the exported module. This issue is fixed in version 3.4.3.

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CVSS v3.1 Score

6.3

MEDIUM

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0007

Probability of exploitation

0.00%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-59 CWE-59

CWE-367 CWE-367

CWE-863 Incorrect Authorization

References

Other References

https://github.com/RsyncProject/rsync/security/advisories/GHSA-4h9m-w5ff-j735

Frequently Asked Questions

What is CVE-2026-44509? +

Rsync is a file-copying tool that uses a delta-transfer algorithm to synchronize remote and local files. In versions prior to 3.4.3, previous bug fixes for symlink races in open() calls missed races in other path based system calls like chmod() and chown(). For rsync daemons with "use chroot = no" this allows an attacker with local filesystem access to change permissions, ownership or timestamp on a file outside the exported module. This issue is fixed in version 3.4.3. It has a CVSS v3.1 base score of 6.3 (MEDIUM).

How severe is CVE-2026-44509? +

CVE-2026-44509 has a CVSS v3.1 score of 6.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0007, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-44509? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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