AWS WAF Vulnerabilities Allow HTTP/2 Multi-Frame Request Bypass
AWS issued a security bulletin for two CVEs in WAF that could let attackers bypass inspection rules via HTTP/2 multi-frame requests.
Key points
- AWS identified two vulnerabilities, CVE-2026-13762 and CVE-2026-13763, in AWS WAF.
- The flaws involve the inspection of request bodies in HTTP/2 multi-frame requests.
- Attackers could potentially bypass WAF security rules by exploiting these issues.
Amazon Web Services (AWS) has published a security bulletin detailing two vulnerabilities in its Web Application Firewall (WAF) service. The advisory, designated as AWS Security Bulletin 2026-048, addresses CVE-2026-13762 and CVE-2026-13763. These issues relate to how AWS WAF inspects request bodies when using the HTTP/2 protocol with multi-frame requests.
The vulnerabilities allow for the potential bypass of WAF inspection rules. According to the official advisory, the core issue lies in the handling of HTTP/2 multi-frame request bodies. When a request is split across multiple frames, the inspection mechanism may not process the full body correctly, allowing malicious payloads to evade detection. This means that security rules configured to block specific content or patterns might fail to trigger if the payload is distributed in this manner.
Context and Background
AWS WAF is a web application firewall that helps protect web applications from common web exploits. It allows customers to define customizable web security rules that control which traffic reaches their applications. The service is often used in conjunction with other AWS services like Amazon CloudFront and Application Load Balancers.
HTTP/2 is a major revision of the HTTP network protocol. It introduces features such as multiplexing, which allows multiple requests and responses to be sent over a single connection simultaneously. This is achieved by breaking data into smaller frames. While this improves performance, it also adds complexity to security inspection tools. The identified vulnerabilities exploit this complexity by leveraging the way multi-frame requests are reconstructed and inspected.
The bulletin does not provide specific details on the severity scores or CVSS ratings for these CVEs. It also does not mention any confirmed exploitation in the wild. However, the nature of the flaw—bypassing security controls—is significant for organizations relying on WAF for protection against web-based attacks.
Who is Affected
All customers using AWS WAF with HTTP/2 traffic are potentially affected. This includes any service or application protected by WAF that accepts HTTP/2 connections. Organizations that have configured WAF rules to inspect request bodies are at risk if those requests are sent via HTTP/2 multi-frame mechanisms.
The impact is limited to the bypass of inspection rules. It does not imply a compromise of the AWS infrastructure itself. However, it does mean that existing security postures relying on WAF for deep packet inspection may be weaker than assumed. Customers who do not use HTTP/2 or who do not inspect request bodies in WAF are not impacted by these specific vulnerabilities.
What should you do?
AWS has not yet confirmed if a patch or update is available for these vulnerabilities. The security bulletin serves as an advisory to inform customers of the issue. Organizations should monitor AWS communications for further updates regarding remediation steps. In the meantime, users should review their WAF configurations and consider the risk of HTTP/2 traffic bypassing inspection rules.
What to do and how to stay safe: AWS
- Review your AWS WAF configurations to understand how HTTP/2 traffic is currently being handled and inspected.
- Monitor AWS security bulletins and official channels for updates on patches or mitigation guidance for CVE-2026-13762 and CVE-2026-13763.
- Consider implementing additional layers of security, such as backend application validation, to compensate for potential WAF inspection gaps.
- Assess whether your applications require HTTP/2 multi-frame requests and if the risk of bypass can be mitigated through other controls until a fix is provided.
Step-by-step guide: Risk Based Vulnerability Management: Prioritize Fixes by Actual Threat
General security guidance from the Threat Times newsroom. It is not confirmed advice from the organisations named in this story.
Frequently asked questions
What are CVE-2026-13762 and CVE-2026-13763?
These are two vulnerabilities in AWS WAF related to the inspection of HTTP/2 multi-frame request bodies, which could allow bypass of security rules.
Is there a patch available for these vulnerabilities?
No, the source material does not confirm that a patch or fix has been released yet.
Who is affected by these vulnerabilities?
Customers using AWS WAF with HTTP/2 traffic who rely on request body inspection are potentially affected.
