CVE-2023-40586 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in github.com/corazawaf/coraza/v3. A fix is available for github.com/corazawaf/coraza/v3 — see the affected versions and patch details below.
go package github.com/corazawaf/coraza is vulnerable to denial of service
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-40586.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
github.com/corazawaf/coraza/v3🐹github.com/corazawaf/coraza/v2Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Summary
Due to the misuse of log.Fatalf, the application using coraza crashed after receiving crafted requests from attackers.
Details
https://github.com/corazawaf/coraza/blob/82157f85f24c6107667bf0f686b71a72aafdf8a5/internal/bodyprocessors/multipart.go#L26-L29
The bodyprocessors of multipart uses log.Fatalf to handle errors from the mime.ParseMediaType, but log.Fatalf calls os.Exit directly after logging the error.
https://github.com/golang/go/blob/a031f4ef83edc132d5f49382bfef491161de2476/src/log/log.go#L288-L291
This means that the application will immediately crash after receiving a malicious request that triggers an error in mime.ParseMediaType.
PoC
The server can be demonstrated by https://github.com/corazawaf/coraza/tree/main/examples/http-server
After sending this request
POST / HTTP/1.1
Host: 127.0.0.1:8090
User-Agent: curl/8.1.2
Accept: */*
Content-Length: 199
Content-Type: multipart/form-data; boundary=------------------------5fa6351b877326a1; a=1; a=2
Connection: close
--------------------------5fa6351b877326a1
Content-Disposition: form-data; name="file"; filename="123"
Content-Type: application/octet-stream
123
--------------------------5fa6351b877326a1--
The server will crash immediately. The a=1; a=2 in Content-Type makes mime: duplicate parameter name error.
Impact
I believe the vulnerability was introduced by the following commit: https://github.com/corazawaf/coraza/commit/24af0c8cf4f10bab558740b595712be3b85493ec.
Mitigation
The error from mime.ParseMediaType should return directly.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/corazawaf/coraza/v3 | ≥ 3.0.0&&< 3.0.1 | 3.0.1go get github.com/corazawaf/coraza/v3@v3.0.1 |
| 🐹Go | github.com/corazawaf/coraza/v2 | ≥ 2.0.0 | No fix |
Affected Products
corazacorazaDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/corazawaf/coraza/v3, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/corazawaf/coraza/v3 to 3.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-40586 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Frequently Asked Questions
Is CVE-2023-40586 in your dependencies?
Find it across Go, including transitive dependencies.