CVE-2026-71847
Description
A flaw was found in Ruby JSON. A heap-use-after-free vulnerability exists in the JSON::ResumableParser component. A remote attacker, by supplying a specially crafted JSON stream with truncated duplicate keys, can cause the application to dereference freed memory. This can lead to process termination, resulting in a Denial of Service (DoS).
Statement
This flaw has a Moderate impact. A heap-use-after-free in the Ruby json gem's native C extension can terminate the Ruby process (denial of service) when an application uses the JSON::ResumableParser streaming API and calls partial_value on incomplete, attacker-controlled input containing duplicate object keys. Red Hat products are not affected: the json gem versions shipped are either outside the vulnerable range (2.20.0-2.21.1), or - where an in-range version is present (Red Hat 3scale API Management's zync component, json 2.21.1) - the application only performs standard whole-buffer JSON.parse and never invokes the vulnerable JSON::ResumableParser#partial_value code path. Exploitation requires the specialized resumable/streaming parser API, which is not used by any affected Red Hat product.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.9 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | High | N/A | N/A |
| Privileges Required | None | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
If the expired pointer is used in a read operation, an attacker might be able to control data read in by the application.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If the expired pointer references a memory location that is not accessible to the product, or points to a location that is "malformed" (such as NULL) or larger than expected by a read or write operation, then a crash may occur.
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If the expired pointer is used in a function call, or points to unexpected data in a write operation, then code execution may be possible.
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