Bug 2563571 (CVE-2026-118673)

Summary: CVE-2026-118673 keepassxc: KeePassXC: Denial of Service (DoS) via out-of-bounds write in browser integration
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in KeePassXC. A local user with access to the inter-process communication (IPC) interface and an authorized database association can cause a Denial of Service (DoS) by crashing the application. By prompting an unlocked database to generate and encrypt an excessively large response through the browser integration component, the application triggers an out-of-bounds write beyond the allocated buffer, terminating the process.
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Description OSIDB Bzimport 2026-10-29 17:45:13 UTC 
KeePassXC is a cross-platform community-driven port of the Windows application KeePass Password Safe. From 2.3.0 until 2.8.0, KeePassXC browser integration encrypts authorized responses in src/browser/BrowserMessageBuilder.cpp using a fixed 1 MiB output vector even though Botan::Sodium::crypto_box_easy() writes the plaintext length plus crypto_box_MACBYTES. A browser-protocol client that can access the per-user IPC endpoint, has a valid database association, and causes an unlocked database to generate and encrypt a sufficiently large authorized response can trigger a sequential out-of-bounds write before any response is delivered. This issue is fixed in version 2.8.0.