Executive Summary
In June 2026, a critical denial-of-service vulnerability, CVE-2026-49975, known as the "HTTP/2 Bomb," was disclosed. This flaw exploits the HPACK compression and flow control features of the HTTP/2 protocol, allowing attackers to send minimal requests that rapidly exhaust server memory. Major web servers, including NGINX, Apache HTTPD, Microsoft IIS, Envoy, and Cloudflare Pingora, are affected in their default configurations. The attack can be executed remotely without authentication, leading to immediate service disruptions. (imperva.com)
The discovery of this vulnerability underscores the evolving threat landscape, where attackers leverage protocol features to amplify attacks. Organizations must prioritize patching affected systems and consider implementing additional security measures, such as Web Application Firewalls (WAFs), to mitigate potential exploits. (imperva.com)
Why This Matters Now
The "HTTP/2 Bomb" vulnerability (CVE-2026-49975) poses an immediate threat to organizations relying on HTTP/2-enabled web servers. Given the widespread adoption of HTTP/2 and the ease of exploit, unpatched systems are at high risk of denial-of-service attacks, leading to significant operational disruptions. Prompt patching and enhanced security measures are crucial to safeguard against potential exploits. (imperva.com)
Attack Path Analysis
An attacker exploits the HTTP/2 Bomb vulnerability (CVE-2026-49975) by sending crafted HTTP/2 requests to a vulnerable web server, leading to memory exhaustion and denial of service. The attack does not involve privilege escalation, lateral movement, command and control, or data exfiltration, but directly impacts the availability of the targeted service.
Kill Chain Progression
Initial Compromise
Description
An attacker sends specially crafted HTTP/2 requests to a vulnerable web server, exploiting the HTTP/2 Bomb vulnerability (CVE-2026-49975) to initiate a denial-of-service condition.
Related CVEs
CVE-2026-49975
CVSS 7.5A memory allocation vulnerability in Apache HTTP Server's mod_http module allows unauthenticated remote attackers to cause a denial of service via malicious HTTP requests.
Affected Products:
Apache Software Foundation Apache HTTP Server – 2.4.17 through 2.4.67
Exploit Status:
proof of concept
MITRE ATT&CK® Techniques
Application Exhaustion Flood
Application or System Exploitation
Service Exhaustion Flood
OS Exhaustion Flood
Potential Compliance Exposure
Mapping incident impact across multiple compliance frameworks.
PCI DSS 4.0 – Maintain an inventory of system components that are in scope for PCI DSS
Control ID: 6.4.1
NYDFS 23 NYCRR 500 – Penetration Testing and Vulnerability Assessments
Control ID: 500.05
DORA – ICT Risk Management Framework
Control ID: Article 5
CISA ZTMM 2.0 – Network and Environment Segmentation
Control ID: Pillar 3
NIS2 Directive – Cybersecurity Risk Management Measures
Control ID: Article 21
Sector Implications
Industry-specific impact of the vulnerabilities, including operational, regulatory, and cloud security risks.
Telecommunications
HTTP/2 Bomb DoS attacks critically threaten telco infrastructure managing large-scale traffic, with 25% of vulnerable servers belonging to communications industries requiring immediate patching.
Health Care / Life Sciences
Healthcare organizations face severe disruption risks from HTTP/2 amplification attacks affecting 17% of vulnerable servers, threatening patient care systems and HIPAA compliance requirements.
Information Technology/IT
IT sector represents 18% of HTTP/2 vulnerable servers with widespread nginx/Apache deployments, facing high DoS risk from easily executable attacks using publicly available proof-of-concept.
Media Production
Media organizations utilizing HTTP/2 for content delivery face significant DoS vulnerabilities affecting distributed web infrastructure, requiring urgent server patches to maintain service availability.
Sources
- HTTP/2 Bomb Attacks Put Telcos, Healthcare Orgs at Riskhttps://www.darkreading.com/vulnerabilities-threats/http-2-bomb-attacks-telcos-healthcareVerified
- Apache HTTP Server 2.4 vulnerabilitieshttps://httpd.apache.org/security/vulnerabilities_24.htmlVerified
- NVD - CVE-2026-49975https://nvd.nist.gov/vuln/detail/CVE-2026-49975Verified
Frequently Asked Questions
Cloud Native Security Fabric Mitigations and ControlsCNSF
Aviatrix Zero Trust CNSF is pertinent to this incident as it can limit the impact of denial-of-service attacks by enforcing strict workload isolation and controlling inbound traffic, thereby reducing the attack surface and potential service disruptions.
Control: Cloud Native Security Fabric (CNSF)
Mitigation: The attacker's ability to exploit the vulnerability would likely be constrained by limiting unauthorized inbound traffic to the web server.
Control: Zero Trust Segmentation
Mitigation: Not applicable, as the attack does not involve privilege escalation.
Control: East-West Traffic Security
Mitigation: Not applicable, as the attack does not involve lateral movement.
Control: Multicloud Visibility & Control
Mitigation: Not applicable, as the attack does not establish command and control channels.
Control: Egress Security & Policy Enforcement
Mitigation: Not applicable, as the attack does not involve data exfiltration.
The potential impact on service availability could be reduced by limiting unauthorized inbound traffic and enforcing workload isolation.
Impact at a Glance
Affected Business Functions
- Web Services
- Customer Portals
- Online Transactions
Estimated downtime: 3 days
Estimated loss: $50,000
No sensitive data exposure reported.
Recommended Actions
Key Takeaways & Next Steps
- • Implement inline intrusion prevention systems (IPS) to detect and block malicious HTTP/2 traffic patterns associated with CVE-2026-49975.
- • Apply patches and updates to web servers to address the HTTP/2 Bomb vulnerability and prevent exploitation.
- • Configure web servers to limit the number of headers per request and manage flow-control windows to mitigate potential abuse.
- • Monitor server memory usage and HTTP/2 traffic for signs of exploitation attempts.
- • Educate security teams about the HTTP/2 Bomb vulnerability and the importance of timely patching and configuration management.
