CVE-2025-30153

Improper Handling of Highly Compressed Data (Data Amplification) in github.com/getkin/kin-openapi/openapi3filter

openapi: 3.0.0
info:
  title: 'Validator'
  version: 0.0.1
paths:
  /:
    post:
      requestBody:
        required: true
        content:
          multipart/form-data:
            schema:
              type: object
              required:
                - file
              properties:
                file:
                  type: string
                  format: binary
      responses:
        '200':
          description: Created

package main

import (
	"fmt"
	"log"
	"net/http"

	"github.com/getkin/kin-openapi/openapi3filter"
	legacyrouter "github.com/getkin/kin-openapi/routers/legacy"

	"github.com/getkin/kin-openapi/openapi3"
)

func handler(w http.ResponseWriter, r *http.Request) {
	loader := openapi3.NewLoader()

	doc, err := loader.LoadFromFile("schema.yaml")
	if err != nil {
		http.Error(w, "Failed to load OpenAPI document", http.StatusInternalServerError)
		return
	}

	if err := doc.Validate(r.Context()); err != nil {
		http.Error(w, "Invalid OpenAPI document", http.StatusBadRequest)
		return
	}

	router, err := legacyrouter.NewRouter(doc)
	if err != nil {
		http.Error(w, "Failed to create router", http.StatusInternalServerError)
		return
	}

	route, pathParams, err := router.FindRoute(r)
	if err != nil {
		http.Error(w, "Failed to find route", http.StatusNotFound)
		return
	}

	input := &openapi3filter.RequestValidationInput{
		Request:     r,
		QueryParams: r.URL.Query(),
		Route:       route,
		PathParams:  pathParams,
	}

	if err := openapi3filter.ValidateRequest(r.Context(), input); err != nil {
		http.Error(w, fmt.Sprintf("Request validation failed: %v", err), http.StatusBadRequest)
		return
	}

	w.Write([]byte("request ok !"))
}

func main() {
	http.HandleFunc("/", handler)
	log.Fatal(http.ListenAndServe(":8080", nil))

}

perl -e 'print "0" x 5000000000' > /tmp/bigfile.txt; zip -9 /tmp/bomb.zip /tmp/bigfile.txt

An attacker can trigger an out-of-memory (OOM) condition, leading to server crashes or degraded performance.
It seems to only be exploitable if the OpenAPI schema allows for multipart upload.

CVE-2025-30153 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.131.0); upgrading removes the vulnerable code path.

Kodem intelligence

Already deployed Kodem?

I see at least 2 potential fixes/improvements:

• Do not register by default the zip file decoder (I honestly was a bit surprised to see it was enabled by default, it seems to be quite a niche use-case ?)
• Update ZipFileBodyDecoder to enforce a maximum size of the decompressed archive and bailout as soon as it's reached (probably with a small default value and allow the users to configure it through the input options ?)

1. What is CVE-2025-30153? CVE-2025-30153 is a high-severity security vulnerability in github.com/getkin/kin-openapi (go), affecting versions < 0.131.0. It is fixed in 0.131.0.
2. How severe is CVE-2025-30153? CVE-2025-30153 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/getkin/kin-openapi are affected by CVE-2025-30153? github.com/getkin/kin-openapi (go) versions < 0.131.0 is affected.
4. Is there a fix for CVE-2025-30153? Yes. CVE-2025-30153 is fixed in 0.131.0. Upgrade to this version or later.
5. Is CVE-2025-30153 exploitable, and should I be worried? Whether CVE-2025-30153 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2025-30153 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2025-30153? Upgrade github.com/getkin/kin-openapi to 0.131.0 or later.