Summary
Low severity vulnerability that affects com.linecorp.armeria:armeria
Multiple timing attack vulnerabilities leading to the recovery of secrets based on the use of non-constant time compare function
Potentially vulnerable codes
https://github.com/line/armeria/blob/f0d870fde1088114070be31b67f7df0a21e835c6/core/src/main/java/com/linecorp/armeria/server/auth/OAuth2Token.java#L54
https://github.com/line/armeria/blob/f0d870fde1088114070be31b67f7df0a21e835c6/core/src/main/java/com/linecorp/armeria/server/auth/BasicToken.java#L64
Workarounds
- Update to the latest version (TBD)
2-1. Users can prevent these vulnerabilities by modifying and implementing timing attack preventions by themselves.
2-2. Precisely speaking, it is possible to compare credentials by securely comparing them after calling methods to directly return the input (namely Object. accessToken(), Object.username() and Object.password()).
References
- https://cwe.mitre.org/data/definitions/208.html
- https://security.stackexchange.com/questions/111040/should-i-worry-about-remote-timing-attacks-on-string-comparison
Side Note
Since it is a theoretical attack, there is no PoC available from neither the vendor nor the security team.
Impact
String comparison method in multiple authentication validation in Armeria were known to be vulnerable to timing attacks. This vulnerability is caused by the insecure implementation of equals method from java.lang.String. While this attack is not practically possible, an attacker still has a potential to attack if the victim's server validates user by using equals method.
We would like to thank @chrsow for pointing out the issue.
CVE-2019-16771 has a CVSS score of 4.8 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.97.0); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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There are two options to patch this issue.
Remove
equalsmethod; it has been exclusively used for test cases and was never used in any OSS projects that are using Armeria. (But it is worth noting that there are possibilities of closed projects authenticating users by utilizingequalsmethod)Use
MessageDigest.isEqualto compare the credential instead.
Frequently Asked Questions
- What is CVE-2019-16771? CVE-2019-16771 is a medium-severity security vulnerability in com.linecorp.armeria:armeria (maven), affecting versions >= 0.50.0, < 0.97.0. It is fixed in 0.97.0.
- How severe is CVE-2019-16771? CVE-2019-16771 has a CVSS score of 4.8 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of com.linecorp.armeria:armeria are affected by CVE-2019-16771? com.linecorp.armeria:armeria (maven) versions >= 0.50.0, < 0.97.0 is affected.
- Is there a fix for CVE-2019-16771? Yes. CVE-2019-16771 is fixed in 0.97.0. Upgrade to this version or later.
- Is CVE-2019-16771 exploitable, and should I be worried? Whether CVE-2019-16771 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2019-16771 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2019-16771? Upgrade
com.linecorp.armeria:armeriato 0.97.0 or later.