CVE-2026-21577

HIGH
MEDIUM Priority: 0.03 BB Relevance: 64/100
Published: 2026-07-21 Modified: 2026-10-24 First seen: 2026-10-29 Status: active

Attack Surface

Network Low Complexity No Interaction

CVSS Vector Breakdown

AV: Network
AC: Low
PR: Low
UI: None
S: X
AT: None
VC: None
VI: None
VA: High

Description

This High severity DoS (Denial of Service) vulnerability was introduced in versions 9.0.1, 9.1.0, 9.2.0, 9.3.1, 9.4.0, 9.5.1, 10.0.2, 10.1.0 and 10.2.0 of Confluence Data Center. This DoS (Denial of Service) vulnerability, with a CVSS Score of 7.1, allows an authenticated attacker to cause a resource to be unavailable for its intended users by temporarily or indefinitely disrupting services of a host connected to a network. Atlassian recommends that Confluence 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: Confluence Data Center 9.2: Upgrade to a release greater than or equal to 9.2.17 Confluence Data Center 10.2: Upgrade to a release greater than or equal to 10.2.7 See the release notes ([https://confluence.atlassian.com/doc/confluence-release-notes-327.html]). You can download the latest version of Confluence Data Center from the download center ([https://www.atlassian.com/software/confluence/download-archives]). This vulnerability was reported via our Penetration Testing program.

Weakness Classification (1)

Affected Software (9)

VendorProductVersion
atlassian confluence_data_center 9.0.1 – 9.0.3
atlassian confluence_data_center 9.1.0 – 9.1.1
atlassian confluence_data_center 9.2.0 – 9.2.15
atlassian confluence_data_center 9.3.1 – 9.3.2
atlassian confluence_data_center 9.4.0 – 9.4.1
atlassian confluence_data_center 9.5.1 – 9.5.4
atlassian confluence_data_center 10.0.2 – 10.0.3
atlassian confluence_data_center 10.1.0 – 10.1.2
atlassian confluence_data_center 10.2.0 – 10.2.6

Bug Bounty Relevance

64 / 100
✓ Network accessible
✓ Low complexity
✓ No user interaction

CVSS Score

7.1 / 10.0 v4.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS — Exploitation Probability

0.43%
Raw Score 0.004260
Percentile 36.8%
Date 2026-10-29

EPSS Trend

2026-10-29
0.00426
2026-10-28
0.00426

Intelligence Sources

nvd ref →