AWS Security Bulletins: CVE-2026-84851- Uncontrolled recursion in the Ion reader in Amazon Ion-C before 1.1.6
AWS Security Bulletins has published a new security advisory. Here is a summary and what to do.
Key points
- New advisory from AWS Security Bulletins.
- Review affected versions in the advisory.
- Apply updates promptly.
AWS Security Bulletins published a security advisory titled “CVE-2026-84851- Uncontrolled recursion in the Ion reader in Amazon Ion-C before 1.1.6”.
At a glance
- Publisher
- AWS Security Bulletins
- CVEs
- CVE-2026-84851
What the advisory says
Bulletin ID: 2026-094-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 09/02/2026 13:30 AM PDT Description: Amazon Ion-C (ion-c) is the C implementation of the Amazon Ion data serialization format. It is distributed as an open-source library (amazon-ion/ion-c) that applications embed to read and write Ion text and binary data. We identified CVE-2026-84851, an uncontrolled recursion issue in versions before 1.1.6 that might allow a remote unauthenticated actor to craft Ion data that exhausts the native call stack and crashes the application using the library, resulting in a denial of service. Impacted versions: < 1.1.6 Please refer to the article below for the most up-to-date and complete information related to this AWS Security Bulletin.
What should you do?
- Read the full vendor advisory linked below and confirm whether you run affected versions.
- Schedule the recommended update, prioritising internet-facing systems.
- Watch for exploitation reports; unpatched edge devices are frequent targets.
What to do and how to stay safe: CVE-2026-84851
- Vulnerability severity scores ignore your specific architecture and context.
- Exploitability depends on network exposure and user behavior, not just code flaws.
- Prioritization requires continuous asset inventory and threat intelligence alignment.
Risk-based vulnerability management focuses your limited resources on the flaws that actually threaten your business. Start by mapping your critical assets and checking for active exploits to prioritize your backlog.
Step-by-step guide: Risk-Based Vulnerability Management: Prioritize Fixes by Actual Danger
General security guidance from the Threat Times newsroom. It is not confirmed advice from the organisations named in this story.
