WS-2026-0043
Published:July 21, 2026
Updated:September 01, 2026
Denial of service via exponential $ref expansion in ExpandSpec/ExpandSchema in github.com/go-openapi/spec. The expander inlines every $ref without memoization or a global budget, so a self-contained specification where each of N definitions references the next one twice expands to 2^N schema nodes from O(N) bytes of input, exhausting CPU and memory. Fixed in v0.22.7 by capping the expanded node count (ExpandOptions.MaxExpansionNodes, bounded by default).
Affected Packages
https://github.com/go-openapi/spec.git (GITHUB):
Affected version(s) >=v0.17.0 <v0.22.7Fix Suggestion:
Update to version v0.22.7github.com/go-openapi/spec (GO):
Affected version(s) >=d1008324672f1909000e2bdad2a1296007ef3b7d <v0.22.7Fix Suggestion:
Update to version v0.22.7Related Resources (2)
Do you need more information?
Contact UsCVSS v4
Base Score:
8.7
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Weakness Type (CWE)
Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')