Summary
Improper Neutralization of CRLF Sequences in HTTP Headers in Jooby ('HTTP Response Splitting)
Workarounds
If you are unable to update, ensure that user supplied data isn't able to flow to HTTP headers. If it does, pre-sanitize for CRLF characters.
References
CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Response Splitting')
I've been poking at libraries to see if they are vulnerable to HTTP Response Splitting and Jooby is my third case of finding this vulnerability.
Root Cause
This roots cause back to this line in the Jooby codebase:
The DefaultHttpHeaders takes a parameter validate which, when true (as it is for the no-arg constructor) validates that the header isn't being abused to do HTTP Response Splitting.
Reported By
This vulnerability was reported by @JLLeitschuh (Twitter)
For more information
If you have any questions or comments about this advisory:
- Open an issue in jooby-project/jooby
Impact
- Cross Site Scripting
- Cache Poisoning
- Page Hijacking
CVE-2020-7622 has a CVSS score of 9.8 (Critical). 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 (2.2.1); 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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This was fixed in version 2.2.1.
Frequently Asked Questions
- What is CVE-2020-7622? CVE-2020-7622 is a critical-severity security vulnerability in io.jooby:jooby-netty (maven), affecting versions < 2.2.1. It is fixed in 2.2.1.
- How severe is CVE-2020-7622? CVE-2020-7622 has a CVSS score of 9.8 (Critical). 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 io.jooby:jooby-netty are affected by CVE-2020-7622? io.jooby:jooby-netty (maven) versions < 2.2.1 is affected.
- Is there a fix for CVE-2020-7622? Yes. CVE-2020-7622 is fixed in 2.2.1. Upgrade to this version or later.
- Is CVE-2020-7622 exploitable, and should I be worried? Whether CVE-2020-7622 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-2020-7622 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-2020-7622? Upgrade
io.jooby:jooby-nettyto 2.2.1 or later.