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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 the provided context also indicates 4.7.0rc0 is affected. The flaw is rooted in Encrypted Client Hello (ECH) transcript reconstruction, specifically in processing of ech_outer_extensions, where an integer truncation error causes incorrect buffer boundary calculation and results in attacker-controlled data being written past the end of a heap-allocated buffer. The overflow has been reported as approximately 245 bytes. The issue can be triggered when Wireshark parses malformed TLS ClientHello traffic containing crafted ECH outer extensions, either from live captured traffic or from a malicious packet capture file such as pcapng.
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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.
A heap-based buffer overflow in Wireshark's TLS dissector ECH transcript reconstruction code that can be triggered by malicious live traffic or a crafted capture file, leading to denial of service or possible code execution.
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