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Description

Heap Overflow in TLS 1.3 ECH parsing. An integer underflow existed in ECH extension parsing logic when calculating a buffer length, which resulted in writing beyond the bounds of an allocated buffer. Note that in wolfSSL, ECH is off by default, and the ECH standard is still evolving.

PUBLISHED Reserved 2026-03-04 | Published 2026-03-19 | Updated 2026-03-24 | Assigner wolfSSL




HIGH: 8.3CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:H/SC:L/SI:L/SA:L

Problem types

CWE-122 Heap-based buffer overflow

Product status

Default status
unaffected

Any version before 5.9.0
affected

Credits

Oleh Konko for independently reporting after internal wolfSSL findings and testing wolfSSL's fix other

References

github.com/wolfSSL/wolfssl/pull/9817

cve.org (CVE-2026-3549)

nvd.nist.gov (CVE-2026-3549)

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