CVE-2021-31866

Name: CVE-2021-31866
Creator: NVD / NIST
Published: 2021-04-28T07:15:07.663+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10EPSS 1.21%

Last modified Jun 17, 2026

CVE-2021-31866 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. Redmine before 4.0.9 and 4.1.x before 4.1.3 allows an attacker to learn the values of internal authentication keys by observing timing differences in string comparison operations within SysController and MailHandlerController.. EPSS estimates a 1.21% chance of exploitation in the next 30 days.

Description

Redmine before 4.0.9 and 4.1.x before 4.1.3 allows an attacker to learn the values of internal authentication keys by observing timing differences in string comparison operations within SysController and MailHandlerController.

Metrics

CVSS 3.1

5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS Probability

1.21%

64.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-203

Affected Software

Vendor	Product	Versions
Redmine	Redmine	< 4.0.9
Redmine	Redmine	>= 4.1.0, < 4.1.3
Debian	Debian Linux	9.0

References

https://lists.debian.org/debian-lts-announce/2021/05/msg00013.htmlMailing List, Third Party Advisory
https://www.redmine.org/news/131Vendor Advisory
https://www.redmine.org/projects/redmine/wiki/Security_AdvisoriesVendor Advisory
https://lists.debian.org/debian-lts-announce/2021/05/msg00013.htmlMailing List, Third Party Advisory
https://www.redmine.org/news/131Vendor Advisory
https://www.redmine.org/projects/redmine/wiki/Security_AdvisoriesVendor Advisory

Timeline

Published: Apr 28, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-31866?

How severe is CVE-2021-31866?

CVE-2021-31866 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 1.21% probability of exploitation in the next 30 days.

How do I fix CVE-2021-31866?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-31866?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST