CVE-2026-70454: rsync < 3.5.0 TLS Certificate Validation Bypass via SSL/OpenSSL Mode

Severity: high (CVSS 8.0 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-13 · updated 2026-10-24
Weakness: CWE-295

Description

rsync 3.2.0 through 3.2.3 (openssl mode) and rsync-ssl through 3.4.4 (stunnel mode) contain a TLS certificate validation vulnerability that allows on-path attackers to intercept encrypted sessions by presenting self-signed or otherwise invalid certificates. Attackers can exploit the failure to validate server TLS certificates against a trusted CA or verify certificate hostname matching to decrypt or tamper with rsync session content without detection by the client.

Affected products

RsyncProject rsync: through 3.4.4

References

https://github.com/RsyncProject/rsync/releases/tag/v3.5.0
https://github.com/RsyncProject/rsync/security/advisories/GHSA-3c3x-ww2w-5r5p
https://www.vulncheck.com/advisories/rsync-tls-certificate-validation-bypass-via-ssl-openssl-mode

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