What is CVE-2021-27924?

CVE-2021-27924 is a medium-severity vulnerability in Couchbase Server, classified under Cleartext Transmission of Sensitive Information. CVSS score: 5.9/10. Published 2021-05-19.

How severe is CVE-2021-27924?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Vulnerability in Couchbase Server

CVE-2021-27924

An issue was discovered in Couchbase Server 6.x through 6.6.1. The Couchbase Server UI is insecurely logging session cookies in the logs. This allows for the impersonation of a user if the log files are obtained by an attacker before a session cookie expires.

Published 2021-05-19 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.005 (43.7th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 44th percentile — 43.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000

Affected products

Couchbase Server

Weakness classification (CWE)

CWE-319 — Cleartext Transmission of Sensitive Information

References

www.couchbase.com/resources/security (Vendor Advisory)
www.couchbase.com/downloads (Product, Vendor Advisory)

Frequently asked questions

What is CVE-2021-27924?: CVE-2021-27924 is a medium-severity vulnerability in Couchbase Server, classified under Cleartext Transmission of Sensitive Information. CVSS score: 5.9/10. Published 2021-05-19.
How severe is CVE-2021-27924?: Medium severity. CVSS v3 base score is 5.9 out of 10.