CVE-2021-31866

MEDIUMNVD 5.35.3—

5.3

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.

CVSS v3: 5.3
EG Score: 5.3(medium)
EPSS: 63.6%
KEV: Not listed

Published

April 28, 2021

Last Modified

November 21, 2024

References (6)

cve@mitrehttps://lists.debian.org/debian-lts-announce/2021/05/msg00013.html
cve@mitrehttps://www.redmine.org/news/131
cve@mitrehttps://www.redmine.org/projects/redmine/wiki/Security_Advisories
af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2021/05/msg00013.html
af854a3a-2127-422b-91ae-364da2661108https://www.redmine.org/news/131
af854a3a-2127-422b-91ae-364da2661108https://www.redmine.org/projects/redmine/wiki/Security_Advisories

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

CWE-203Observable Discrepancy (Information Exposure via Side Channel)

Data Freshness Timeline

(refreshed 12× in last 7d / 20× in last 30d)

Every time one of our enrichment pipelines (NVD, MITRE cvelistV5, EPSS, CISA KEV, GHSA, OSV, vendor advisories) ran against this CVE. Most recent first.

2026-06-02 20:11 UTCepss_batch
2026-06-02 20:11 UTCepss_batch
2026-06-01 13:50 UTCepss_batch
2026-06-01 13:50 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 00:15 UTCepss_batch
2026-05-31 00:15 UTCepss_batch
2026-05-29 13:42 UTCepss_batch
2026-05-29 13:42 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-26 17:22 UTCEG score recompute
2026-05-26 17:21 UTCGHSA enrichment
2026-05-26 13:42 UTCepss_batch
2026-05-26 07:46 UTCOSV refresh
2026-05-26 07:17 UTCepss_batch

Frequently asked(5)

What is CVE-2021-31866?

CVE-2021-31866 is a medium vulnerability published on April 28, 2021. 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.

When was CVE-2021-31866 disclosed?

CVE-2021-31866 was first published in the National Vulnerability Database on April 28, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-31866 actively exploited?

CVE-2021-31866 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 63.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-31866?

CVE-2021-31866 has a CVSS v3 base score of 5.3 (NVD).

How do I remediate CVE-2021-31866?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-31866, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2021-31866

Explore →

Is Your Infrastructure Affected by CVE-2021-31866?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs

CVE-2021-31866

📅 Published

🔄 Last Modified

🔗 References (6)

Weakness Classification(1)

Data Freshness Timeline

❓ Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-31866?

🔗 Related CVEs(same CWE)

Same CWE

Published

Last Modified

References (6)

Frequently asked(5)

Related CVEs(same CWE)