CVE-2026-77354: getkin kin-openapi Uncontrolled Resource Consumption

Vulnerability summary

CVE-2026-77354 is a high (CVSS 8.7) Uncontrolled Resource Consumption vulnerability in getkin kin-openapi. EPSS estimates a 0.52% chance of exploitation in the next 30 days, higher than 43.2% of scored vulnerabilities.

Timeline

1. 21-08-2026
   PublishedVulnerability first disclosed.
2. 25-08-2026
   Last modifiedVulnerability information updated.

Description

kin-openapi is a Go project for handling OpenAPI files. From 0.124.0 until 0.142.0, openapi3filter.sliceMapToSlice in openapi3filter/req_resp_decoder.go converts attacker-controlled sparse indexes from a deepObject query parameter into a dense slice by allocating entries from zero through the largest supplied index, after which buildResObj creates another slice of the same length. This allocation occurs before schema validation, so maxItems does not prevent it. An unauthenticated client can send a small query such as param[items][50000000]=x to an endpoint whose deepObject schema contains an array, forcing multi-gigabyte heap allocation and causing an OOM kill or restart loop. Other request-body encodings and styled parameters that do not produce bracketed integer indexes are not affected. This issue is fixed in version 0.142.0.

• CWE-400Uncontrolled Resource ConsumptionThe product does not properly control the allocation and maintenance of a limited resource.
• CWE-789Memory Allocation with Excessive Size ValueThe product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated.