CVE-2017-18239: A time-sensitive equality check on the JWT signature in the JsonWebToken.validate method in main/scala/authent

Q: How do I fix CVE-2017-18239?

authentikat-jwt: upgrade to newer than 0.4.5. Exact commands for each OS are on this page.

Q: Is CVE-2017-18239 being exploited?

CVE-2017-18239 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2017-18239 affect?

CVE-2017-18239 affects authentikat-jwt. Severity is critical (CVSS 9.8). A time-sensitive equality check on the JWT signature in the JsonWebToken.validate method in main/scala/authentikat/jwt/JsonWebToken.scala in authentikat-jwt (aka com.jason-goodwin/authentikat-jwt) version 0.4.5 and earlier allows the suppli

Q: How urgent is CVE-2017-18239?

Priority 59/100. Critical severity; Remotely exploitable, no login, no user action

This month

CRITICAL 9.8REMOTEUPGRADE

CVE-2017-18239 is a critical-severity flaw (CVSS 9.8) affecting authentikat-jwt. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A time-sensitive equality check on the JWT signature in the JsonWebToken.validate method in main/scala/authentikat/jwt/JsonWebToken.scala in authentikat-jwt (aka com.jason-goodwin/authentikat-jwt) version 0.4.5 and earlier allows the supplier of a JWT token to guess bit after bit of the signature by repeating validation requests.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.0% (top 20%)
CISA exploited list	No
Published	2018-03-18
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: authentikat-jwt project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2018-03-18 03:29 UTCPublished CVE record published
2026-06-17 01:12 UTCUpdated Record last modified

authentikat-jwt project authentikat-jwt UPGRADE

Affected: <= 0.4.5

Fixed in: newer than 0.4.5

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy authentikat-jwt || rpm -q authentikat-jwt || authentikat-jwt --version

2. UPGRADE to newer than 0.4.5 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade authentikat-jwt

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade authentikat-jwt

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2017-18239?

authentikat-jwt: upgrade to newer than 0.4.5. Exact commands for each OS are on this page.

Is CVE-2017-18239 being exploited?

CVE-2017-18239 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2017-18239 affect?

CVE-2017-18239 affects authentikat-jwt. Severity is critical (CVSS 9.8). A time-sensitive equality check on the JWT signature in the JsonWebToken.validate method in main/scala/authentikat/jwt/JsonWebToken.scala in authentikat-jwt (aka com.jason-goodwin/authentikat-jwt) version 0.4.5 and earlier allows the suppli

How urgent is CVE-2017-18239?

Priority 59/100. Critical severity; Remotely exploitable, no login, no user action

References

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