The JIRA Workflow Designer Plugin in Atlassian JIRA Server before 6.3.0 improperly uses an XML parser and deserializer, which allows remote attackers to execute arbitrary code, read arbitrary files, or cause a denial of service via a crafted serialized Java object.
Severity
CVSS 3.0
9.8 critical
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
16% chance of exploitation in the next 30 days; higher than 96% of CVEs (scores of 2026-10-31)