🔍 Read the full analysis: Apache HTTP/2 CVE-2026-119618: A Checklist For Affected Teams on ThorstenMeyerAI.com
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TL;DR
Apache released HTTP Server 2.4.71 on November 11 to fix CVE-2026-119618, a critical flaw in mod_http2 that Apache says can lead to remote code execution. Affected versions include Apache HTTP Server 2.4.55–2.4.70, but exposure requires HTTP/2 to be enabled; teams should check distribution advisories and apply fixed packages. Public reporting on exploitation is mixed, and details about the reported reliable exploit remain unclear.
The Apache HTTP Server project released version 2.4.71 on November 11 to fix CVE-2026-119618, a critical flaw in its mod_http2 module that Apache says can lead to remote code execution. The issue affects Apache HTTP Server versions 2.4.55 through 2.4.70 and standalone mod_h2 releases 2.0.8 through 2.0.42; only servers with HTTP/2 enabled are exposed, according to Red Hat.
Apache describes the flaw as a shared-resource synchronization vulnerability in the mod_http2 function assign_headers, and labels it “heap corruption and RCE in assign_headers.” In plain terms, Red Hat says a thread-safety defect can allow one thread to modify memory being used by another, corrupting the server’s internal memory. Red Hat says a remote attacker who can reach an affected web server could execute commands without authentication. It rates the flaw 9.8 out of 10 on CVSS 3.1; the National Vulnerability Database had not published its own score as of November 12.
The upstream fix is Apache HTTP Server 2.4.71. Red Hat said fixed packages were available November 11, including updates for RHEL 9 and 10. Debian’s stable bookworm and trixie releases were still listed as vulnerable in the source report’s November 12 check; version 2.4.71-1 had reached Debian’s unstable sid branch. The report found no published Ubuntu or SUSE advisory at that time. Teams using distribution packages should verify their vendor’s advisory and package status rather than assume that an upstream version number maps directly to their installation.
The exposure check is configuration as well as version. Red Hat says servers using HTTP/2 through the Protocols directive, whether h2 or h2c, are affected; servers serving only HTTP/1.1 are not. Apache documentation lists HTTP/1.1 as the default protocol setting, but administrators should inspect their actual configuration. The report also says Red Hat Enterprise Linux 8 and earlier are not affected, while Red Hat JBoss Core Services and Red Hat Hardened Images were still marked affected in the vendor information it reviewed.
Apache HTTP/2 flaw Patch and exposure checklist
Apache released a fix for a critical flaw that can enable remote code execution. Teams need to check both server versions and HTTP/2 configuration.
Check whether you are exposed
Affected versions need HTTP/2 enabled to be exposed.
Check Apache HTTP Server 2.4.55–2.4.70 and standalone mod_h2 2.0.8–2.0.42.
Check whether HTTP/2 is enabled through the Protocols directive, including h2 or h2c.
Review cloud instances, containers, and hardened images as well as standard hosts.
Apply the appropriate fix
Package availability differs by operating system and product.
| Action | What teams should do |
|---|---|
| Upstream | Upgrade to Apache HTTP Server 2.4.71. |
| Distribution package | Check the current vendor advisory and install its fixed package. |
| No fix available | Follow vendor guidance; assess whether HTTP/2 can be safely disabled until patched. |
| After patching | Confirm installed package and service state on all affected hosts. |
Exploit status remains unclear
Public accounts differ, and the cited reports do not confirm exploitation in the wild.
- Wiz reported no available exploit and no known in-the-wild exploitation on November 11.
- Red Hat said public research demonstrated a reliable exploit against a default-configured server with mod_http2 enabled.
- The cited Red Hat statement does not identify the research or confirm attacks.
- Advisories did not provide exploit instructions; no public exploit code was linked in the report.
Verify vendor package status
The November 12 report snapshot may not reflect current availability.
Red Hat packages
Red Hat said fixed packages were available November 11, including updates for RHEL 9 and 10.
Debian, Ubuntu, SUSE
Debian stable was listed as vulnerable in the report’s check; no Ubuntu or SUSE advisory was found then. Consult current vendor notices.
Patch Priority for HTTP/2 Servers
The issue matters because it combines remote reachability and potential command execution on a widely used web server. An attacker would not need authentication, according to Red Hat’s description, but the stated exposure depends on the affected module and HTTP/2 being enabled. That makes inventory and configuration checks important alongside patching: a version scan alone may not establish whether a particular deployment is exposed.
Wiz reported that 64% of cloud environments in its customer data had resources it classified as vulnerable and that 51% had publicly exposed instances. Wiz cautioned that its figures do not account for configuration, so they are not a count of confirmed exploitable servers and should not be treated as a measure of all internet-facing Apache installations. They do indicate why cloud and hosting teams may need to identify affected instances quickly.
For organizations relying on Apache to serve applications, a compromise could affect the server and potentially provide a path to systems or data reachable from it. The severity rating and reported exploit research support treating the patch as urgent, while the exact risk for each server depends on its build, configuration, network exposure and vendor packaging.
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Reports, Fix and Vendor Status
Apache credited the discovery to Anthropic’s OSS Scanner and two researchers from Google Cloud Vulnerability Research. According to the project timeline in the source report, Anthropic sent its report on October 26, the CVE number was reserved October 30, and the Google Cloud researchers reported the issue November 3. Apache released the fix November 11, 16 days after the first report.
The source report says Apache’s Eric Covener posted the advisory to the oss-security mailing list at 12:19 UTC on November 11. Red Hat’s CVE entry followed at 12:52 UTC, and the CVE record went public at 14:54 UTC. This timeline matters for administrators tracking vendor announcements: the upstream release and security notices appeared close together, but downstream distribution updates can arrive on different schedules.
Apache’s advisory identifies the vulnerable code path as mod_http2’s assign_headers, where concurrent HTTP/2 requests are handled across threads. HTTP/2 allows multiple requests over one connection, and the module processes parallel requests using several threads. Apache’s description and Red Hat’s explanation identify the synchronization problem, but the advisories do not provide exploit instructions.
““Concurrent Execution using Shared Resource with Improper Synchronization vulnerability in Apache HTTP Server’s mod_http2 in assign_headers() can lead to RCE.””
— Apache HTTP Server project
Exploit Status and Package Coverage
Whether attackers are exploiting the flaw remains unconfirmed. Wiz reported no exploit availability and no known in-the-wild exploitation when it published on November 11. The CVE was not on CISA’s Known Exploited Vulnerabilities catalog when the source report checked on November 12, but the cited catalog version predated the public disclosure. Its omission at that point does not establish that exploitation has not occurred.
Red Hat separately said public research had demonstrated a reliable exploit against a default-configured server with mod_http2 enabled. The cited statement does not name the researchers, say where the research was published, or confirm attacks in the wild. The source report found no public exploit code linked from the advisories. Apache also did not publish technical exploit details.
Vendor coverage was still developing on November 12. Debian stable packages remained listed as vulnerable, and the report found no Ubuntu or SUSE advisory then. Those findings describe the status at the time checked, not necessarily later package availability. Administrators should consult current vendor notices for their specific operating system and product.
Check Configurations and Apply Fixes
Teams should identify Apache HTTP Server and standalone mod_h2 versions in use, determine whether HTTP/2 is enabled, and apply Apache 2.4.71 or the relevant fixed package from their operating-system vendor. Where a fixed package is not yet available, administrators should follow vendor guidance and review whether HTTP/2 can be disabled safely until an update is ready. Configuration changes should be tested against application and service requirements.
After patching, teams should confirm the installed package and service state across all affected hosts, including cloud instances and container or hardened-image deployments. They should also monitor advisories from Apache and their vendors for updated affected-version lists, remediation instructions and exploit-status information. The source material does not give a specific deadline for further updates, so the next milestones are vendor package releases and any verified information about exploitation.
Key Questions
Which Apache versions are affected by CVE-2026-119618?
Apache HTTP Server 2.4.55 through 2.4.70 and standalone mod_h2 versions 2.0.8 through 2.0.42 are listed as affected. Apache’s fixed upstream release is 2.4.71. Check the relevant vendor advisory if Apache was installed through a Linux distribution or bundled product.
Does the flaw affect servers that only use HTTP/1.1?
Red Hat says servers serving only HTTP/1.1 are not affected. The stated exposure requires HTTP/2, enabled as h2 or h2c through Apache’s Protocols directive. Administrators should inspect the server’s actual configuration rather than rely on a default setting.
Is CVE-2026-119618 being exploited in the wild?
The information available in the source report does not confirm in-the-wild exploitation. Wiz reported no known exploitation when it published on November 11, while Red Hat said public research had demonstrated a reliable exploit. The available statements do not establish that attackers have used it.
What should affected teams do now?
Inventory affected Apache and mod_h2 installations, check whether HTTP/2 is enabled, and apply Apache 2.4.71 or the fixed package supplied by the relevant vendor. Where a vendor update is pending, follow its security guidance and reassess whether HTTP/2 can be disabled temporarily without disrupting service.
Source: ThorstenMeyerAI.com
