CVE-2026-77354 kin-openapi: Uncontrolled resource consumption in openapi3filter deepObject query parameter decoding
An unauthenticated attacker can cause a denial of service via memory exhaustion by sending crafted deepObject query parameters to applications using kin-openapi.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-77354?
CVE-2026-77354 is a high-severity denial of service vulnerability in getkin kin-openapi, published on 21 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-77354?
3 open source packages ship an affected version, including github.com/getkin/kin-openapi.
| Package | Affected | Fixed in |
|---|---|---|
github.com/getkin/kin-openapi Go | From 0.124.0 | 0.142.0 |
github.com/getkin/kin-openapi Go | From 0.124.0 | 0.142.0 |
github.com/getkin/kin-openapi Go | From 0.124.0 | 0.142.0 |
How do I fix CVE-2026-77354?
Upgrade github.com/getkin/kin-openapi to 0.142.0 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-77354 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77354 exists.
Sources
Also known as DEBIAN-CVE-2026-77354, GHSA-xhj3-7xw9-vr34, GO-2026-6275, MINI-22x7-qjhx-q5rf, MINI-2h49-f852-972x, MINI-2hmc-6xwq-7pg7 and 41 more.