Bug 2461203 (CVE-2026-6276)

Summary: CVE-2026-6276 curl: libcurl: Information disclosure due to cookie leak when reusing connections with custom Host headers
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerability-draftAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: bbrownin, crizzo, csutherl, dbosanac, jclere, jmitchel, jreimann, kaycoth, kshier, mdessi, mrizzi, pbohmill, pcattana, pjindal, plodge, rhel-process-autobot, sdawley, security-response-team, stcannon, szappis, teagle, vchlup, watson-tool-maintainers, yguenane
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in libcurl. This vulnerability allows for information disclosure when a custom `Host:` header is used in an initial HTTP request, and a subsequent request reuses the same connection without specifying a new `Host:` header. This can lead to libcurl incorrectly sending cookies intended for the first host to the second host, resulting in a cookie leak. This issue is categorized as an Origin Validation Error (CWE-346). Exploitation typically requires specific debugging configurations.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Deadline: 2026-04-29   

Description OSIDB Bzimport 2026-04-23 16:48:30 UTC
A flaw was found in libcurl. This vulnerability allows for information disclosure when a custom `Host:` header is used in an initial HTTP request, and a subsequent request reuses the same connection without specifying a new `Host:` header. In such a scenario, libcurl may incorrectly send cookies intended for the first host to the second host, leading to a cookie leak. This issue is an Origin Validation Error (CWE-346).