Vulnerability Details CVE-2026-3849
Stack Buffer Overflow in wc_HpkeLabeledExtract via Oversized ECH Config. A vulnerability existed in wolfSSL 5.8.4 ECH (Encrypted Client Hello) support, where a maliciously crafted ECH config could cause a stack buffer overflow on the client side, leading to potential remote execution and client program crash. This could be exploited by a malicious TLS server supporting ECH. Note that ECH is off by default, and is only enabled with enable-ech.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.004
EPSS Ranking 59.3%
CVSS Severity
CVSS v3 Score 9.8
References
Products affected by CVE-2026-3849
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cpe:2.3:a:wolfssl:wolfssl:5.6.0
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cpe:2.3:a:wolfssl:wolfssl:5.6.2
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cpe:2.3:a:wolfssl:wolfssl:5.6.3
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cpe:2.3:a:wolfssl:wolfssl:5.6.4
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cpe:2.3:a:wolfssl:wolfssl:5.6.6
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cpe:2.3:a:wolfssl:wolfssl:5.7.0
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cpe:2.3:a:wolfssl:wolfssl:5.7.2
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cpe:2.3:a:wolfssl:wolfssl:5.7.4
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cpe:2.3:a:wolfssl:wolfssl:5.7.6
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cpe:2.3:a:wolfssl:wolfssl:5.8.0
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cpe:2.3:a:wolfssl:wolfssl:5.8.2
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cpe:2.3:a:wolfssl:wolfssl:5.8.4