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CVE-2026-5402 is a heap-based buffer overflow in Wireshark's TLS protocol dissector affecting Wireshark 4.6.0 through 4.6.4, and also reported as affecting 4.7.0rc0. The flaw is in Encrypted Client Hello (ECH) transcript reconstruction, specifically processing of ECH outer extensions, where an integer truncation error causes incorrect buffer boundary calculation during parsing. As a result, attacker-controlled data from a crafted TLS ClientHello can be written past the end of a heap-allocated buffer. The issue has been described as producing an overflow of approximately 245 bytes. The vulnerability can be triggered either during live capture of malicious TLS traffic or when opening a crafted packet capture containing the malformed handshake. The primary consequence is application crash, with possible arbitrary code execution in the context of the user running Wireshark.
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Referenced as part of the Wireshark 4.6.8 advisory/plugin CVE list, but not described individually in the content.
A vulnerability in Wireshark's TLS dissector that can cause a crash and possibly code execution when parsing malformed TLS traffic.
A Wireshark TLS dissector vulnerability that can cause a crash with possible remote code execution when parsing malformed TLS traffic.
A heap overflow vulnerability in the TLS protocol dissector in Wireshark 4.6.0 through 4.6.4 that can lead to denial of service and possible code execution.
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Every observed campaign linking this CVE to a named adversary.
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Cross-references every affected SKU, including bundled OEM variants.
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