Bug 2451798 (CVE-2026-33490)

Summary: CVE-2026-33490 h3: H3: Information disclosure due to incorrect path prefix validation
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: jcantril, rojacob
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in H3, a minimal HTTP framework. The `mount()` method, responsible for routing requests to sub-applications, incorrectly uses a simple string comparison to check path prefixes. This allows a remote attacker to craft a URL that bypasses the intended path segment boundary. Consequently, middleware designed for specific administrative paths could be triggered for unrelated public paths, potentially leading to the exposure of sensitive information or unintended access due to incorrect privilege flags being set in the request context.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2452017, 2452018    
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Description OSIDB Bzimport 2026-03-26 18:01:54 UTC 
H3 is a minimal H(TTP) framework. In versions 2.0.0-0 through 2.0.1-rc.16, the `mount()` method in h3 uses a simple `startsWith()` check to determine whether incoming requests fall under a mounted sub-application's path prefix. Because this check does not verify a path segment boundary (i.e., that the next character after the base is `/` or end-of-string), middleware registered on a mount like `/admin` will also execute for unrelated routes such as `/admin-public`, `/administrator`, or `/adminstuff`. This allows an attacker to trigger context-setting middleware on paths it was never intended to cover, potentially polluting request context with unintended privilege flags. Version 2.0.2-rc.17 contains a patch.