Bug 2542252 (CVE-2026-100888)

Summary: CVE-2026-100888 opendkim: opendkim: Denial of Service via out-of-bounds write in dkim_canon_selecthdrs
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in OpenDKIM. A remote attacker can exploit this flaw to cause a Denial of Service (DoS) or potentially arbitrary code execution by submitting a specially crafted DomainKeys Identified Mail (DKIM) signature header. In the dkim_canon_selecthdrs function, improper processing of the 'h' header tag triggers an out-of-bounds write and memory corruption.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2542280, 2542281    
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Description OSIDB Bzimport 2026-09-27 23:41:19 UTC 
A weakness has been identified in Trusted Domain Project OpenDKIM up to 2.11.0. This affects the function dkim_canon_selecthdrs of the file libopendkim/dkim-canon.c of the component DKIM Signature Header Selection. Executing a manipulation of the argument h can lead to out-of-bounds write. The attack can be executed remotely. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.