CVE-2019-16771 is a medium-severity (CVSS 6.5) vulnerability in com.linecorp.armeria:armeria. A fix is available for com.linecorp.armeria:armeria — see the affected versions and patch details below.
Low severity vulnerability that affects com.linecorp.armeria:armeria
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2019-16771 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 379,145 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
com.linecorp.armeria:armeriaReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
Multiple timing attack vulnerabilities leading to the recovery of secrets based on the use of non-constant time compare function
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.
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
Patches
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.
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | com.linecorp.armeria:armeria | ≥ 0.50.0&&< 0.97.0 | 0.97.0com.linecorp.armeria:armeria:0.97.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.linecorp.armeria:armeria, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update com.linecorp.armeria:armeria to 0.97.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-16771 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2019-16771 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2019-16771. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2019-16771 in your dependencies?
O3 Security finds CVE-2019-16771 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.