What is CVE-2026-21571?

CVE-2026-21571 is a high-severity vulnerability in Atlassian Bamboo, classified under OS Command Injection. CVSS score: 8.8/10. Published 2026-04-21.

How severe is CVE-2026-21571?

High severity. CVSS v3 base score is 8.8 out of 10.

RCE in Atlassian Bamboo

CVE-2026-21571

This Critical severity OS Command Injection vulnerability was introduced in versions 9.6.0, 10.0.0, 10.1.0, 10.2.0, 11.0.0, 11.1.0, 12.0.0, and 12.1.0 of Bamboo Data Center. This RCE (Remote Code Execution) vulnerability, with a CVSS Score of 9.4 and a CVSS Vector of CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H allows an authenticated attacker to execute commands on the remote system, which has high impact to confidentiality, high impact to integrity, high impact to availability, and requires no user interaction. Atlassian recommends that Bamboo Data Center customers upgrade to latest version, if you are unable to do so, upgrade your instance to one of the specified supported fixed versions: Bamboo Data Center 9.6.0: Upgrade to a release greater than or equal to 9.6.25 Bamboo Data Center 10.2: Upgrade to a release greater than or equal to 10.2.18 Bamboo Data Center 12.1: Upgrade to a release greater than or equal to 12.1.6 See the release notes ([https://confluence.atlassian.com/bambooreleases/bamboo-release-notes-1189793869.html]). You can download the latest version of Bamboo Data Center from the download center ([https://www.atlassian.com/software/bamboo/download-archives]).

Vulnerability class: Command Injection (OS Command Injection)

Published 2026-04-21 · last modified 2026-08-10.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.013 (70.9th percentile), scored 2026-10-19.

Low probability of exploitation in the next 30 days, but still tracked. 71st percentile — 70.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.013 · newest: 0.013 · change: 0.000

Affected products

Atlassian Bamboo
Atlassian Bamboo Data Center — versions 12.1.0 to 12.1.3, 12.0.0 to 12.0.2, 11.0.0 to 11.0.8

Weakness classification (CWE)

CWE-78 — OS Command Injection

References

confluence.atlassian.com/pages/viewpage.action (Vendor Advisory)
jira.atlassian.com/browse/BAM-26364 (Issue Tracking, Vendor Advisory)

Frequently asked questions

What is CVE-2026-21571?: CVE-2026-21571 is a high-severity vulnerability in Atlassian Bamboo, classified under OS Command Injection. CVSS score: 8.8/10. Published 2026-04-21.
How severe is CVE-2026-21571?: High severity. CVSS v3 base score is 8.8 out of 10.