Coraza: Unbounded recursion in JSON response body processor causes CPU exhaustion

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.9 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-107833: 0.39% estimated exploitation activity in the next 30 days; percentile 32.98 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The JSON response body processor parses response bodies with no recursion limit. ProcessResponse calls readJSON(ss, ignoreJSONRecursionLimit), and that constant is -1. The guard in readItems only fires on == 0, so counting down from -1 (-2, -3, ...) never reaches it. The guard is effectively dead on the response path. The request path is fine: ProcessRequest passes the configured limit (default 1024). There is no equivalent directive or default for responses. Parsing a deeply nested JSON response is CPU-bound and its cost grows quadratically with nesting depth. A 512 KiB response (the default ResponseBodyLimit) holds about 87,000 nesting levels and takes ~12 s to process, keeping one core busy the whole time. Root cause internal/bodyprocessors/json.go The guard and the decrement: Note that ProcessResponse discards BodyProcessorOptions (the parameter is ), so even a caller that wanted to set a limit on responses has no way to. Why the cost is quadratic Every nesting level…

Published by the source

8 Oct 2026, 17:51 UTC

Last modified by the source

19 Oct 2026, 21:40 UTC

Source last checked

26 Oct 2026, 15:32 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-3c6w-j9xm-8h2h

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GO-2026-6690

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-3c6w-j9xm-8h2h

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# Patch Next advisory brief: CVE-2026-107833

Advisory: Coraza: Unbounded recursion in JSON response body processor causes CPU exhaustion
IDs: CVE-2026-107833, GHSA-3c6w-j9xm-8h2h
Record: https://patchnext.com/advisories/cve-2026-107833 (revision 3, source checked 26 Oct 2026, 15:32 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: github.com/corazawaf/coraza/v3 3.8.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/corazawaf/coraza/v3: affected >= 3.0.0, < 3.8.0; fixed in 3.8.0
- Go github.com/corazawaf/coraza: affected every version
- Go github.com/corazawaf/coraza/v2: affected every version

## Suggested inspection (read-only)
- Go github.com/corazawaf/coraza/v3: check the installed version with your package manager.
- Go github.com/corazawaf/coraza: check the installed version with your package manager.
- Go github.com/corazawaf/coraza/v2: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/corazawaf/coraza/v3, github.com/corazawaf/coraza, github.com/corazawaf/coraza/v2.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GO-2026-6690 (OSV record GO-2026-6690 lists affected ranges: Go github.com/corazawaf/coraza >=0; Go github.com/corazawaf/coraza/v2 >=0; Go github.com/corazawaf/coraza/v3 >=3.0.0 <3.8.0 (fixed))
- Verified: https://osv.dev/vulnerability/GHSA-3c6w-j9xm-8h2h (OSV record GHSA-3c6w-j9xm-8h2h lists affected ranges: Go github.com/corazawaf/coraza/v3 >=3.0.0 <3.8.0 (fixed))
- Verified: https://github.com/advisories/GHSA-3c6w-j9xm-8h2h (GitHub-reviewed advisory GHSA-3c6w-j9xm-8h2h lists affected ranges: Go github.com/corazawaf/coraza/v3 >=3.0.0 <3.8.0)

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