CVE-2026-3549: ECH parsing heap buffer overflow
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.
Affected Software
Remediation
Patch Available
Event History
Frequently Asked Questions
What is the severity of CVE-2026-3549?
CVE-2026-3549 is categorized as a high-severity vulnerability due to the potential for a heap buffer overflow in TLS 1.3 ECH parsing.
How do I fix CVE-2026-3549?
To fix CVE-2026-3549, update your wolfSSL library to the latest version where the vulnerability has been addressed.
What impact does CVE-2026-3549 have on affected software?
CVE-2026-3549 can lead to remote code execution or denial of service due to heap buffer overflow resulting from integer underflow in ECH extension parsing.
Is ECH enabled by default in wolfSSL related to CVE-2026-3549?
No, ECH is off by default in wolfSSL, which mitigates the risk of CVE-2026-3549 unless explicitly enabled.
Which versions of wolfSSL are affected by CVE-2026-3549?
CVE-2026-3549 affects all versions of wolfSSL that include the ECH parsing logic without proper fixes.