What’s Vulnerable › Vulnerabilities

CVE-2016-10027

• Severity: medium (CVSS 5.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2017-01-12 · updated 2026-06-17
• Weakness: CWE-362

Description

Race condition in the XMPP library in Smack before 4.1.9, when the SecurityMode.required TLS setting has been set, allows man-in-the-middle attackers to bypass TLS protections and trigger use of cleartext for client authentication by stripping the "starttls" feature from a server response.

Affected products

• Fedoraproject Fedora: 25
• igniterealtime Smack: before 4.1.9 — fixed in 4.1.9

How to fix

Upgrade to a fixed version: igniterealtime Smack 4.1.9. Check the vendor advisory for mitigations.

References

• http://www.openwall.com/lists/oss-security/2016/12/22/12
• http://www.securityfocus.com/bid/95129
• https://community.igniterealtime.org/blogs/ignite/2016/11/22/smack-security-advisory-2016-11-22
• https://github.com/igniterealtime/Smack/commit/059ee99ba0d5ff7758829acf5a9aeede09ec820b
• https://github.com/igniterealtime/Smack/commit/a9d5cd4a611f47123f9561bc5a81a4555fe7cb04
• https://issues.igniterealtime.org/projects/SMACK/issues/SMACK-739
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/J4WXAZ4JVJXHMEDDXJVWJHPVBF5QCTZF/
• http://www.openwall.com/lists/oss-security/2016/12/22/12
• http://www.securityfocus.com/bid/95129
• https://community.igniterealtime.org/blogs/ignite/2016/11/22/smack-security-advisory-2016-11-22
• https://github.com/igniterealtime/Smack/commit/059ee99ba0d5ff7758829acf5a9aeede09ec820b
• https://github.com/igniterealtime/Smack/commit/a9d5cd4a611f47123f9561bc5a81a4555fe7cb04

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