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CISA issues advisory on Apache HTTP Server HTTP/2 remote code execution defect

Abhishek Gawade
Abhishek GawadeinSoBasically
1 min readEdition: 2026-11-12-cybersecurity-advisories
Topographic elevation contour card for CISA issues advisory on Apache HTTP Server HTTP/2 remote code execution defect
VISUAL ARTWORK:Original editorial artwork. Third-party brand marks used under nominative fair use.

What happened.The Apache Software Foundation patched a critical thread-safety vulnerability in mod_http2 as CISA warned of remote code execution risks across web infrastructure.

Why it matters.Apache HTTP Server powers web applications and proxies across enterprise networks. When thread-safety flaws permit remote code execution, attackers compromise edge servers without credentials. Administrators must upgrade web servers to Apache 2.4.71 immediately or disable h2 directives.

The technical specifications:

  • Vulnerability mechanics: Tracked as CVE-2026-119618 with a 9.8 CVSS score, the defect stems from improper synchronization in mod_http2 during concurrent header processing.
  • Race condition: Unauthenticated remote attackers flood servers with concurrent HTTP/2 requests, corrupting shared lock-free memory allocators in assign_headers.
  • Exploitation impact: The resulting heap corruption enables remote unauthenticated attackers to execute arbitrary code with web server process privileges.
  • Affected scope: The defect affects Apache HTTP Server versions 2.4.55 through 2.4.70 and mod_h2 releases 2.0.8 through 2.0.42 when HTTP/2 is active.
  • Remediation release: The Apache Software Foundation published Apache HTTP Server version 2.4.71, advising administrators to upgrade or restrict HTTP/2 protocols.
TOPICS:
#security#web-infrastructure#remote-code-execution#memory-corruption