CVE-2026-3549 ECH parsing heap buffer overflow
An integer underflow in wolfSSL's ECH parsing allows heap buffer overflows, potentially leading to code execution or crashes when ECH is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-3549?
CVE-2026-3549 is a high-severity memory corruption vulnerability in Wolfssl Wolfssl, published on 19 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-122
Which versions are affected by CVE-2026-3549?
It affects 1 product.
Products include Wolfssl Wolfssl.
How do I fix CVE-2026-3549?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-3549 being exploited?
There is no known exploitation of CVE-2026-3549 in the wild and no public exploit code.
Other vulnerabilities in Wolfssl Wolfssl
Sources
Also known as DEBIAN-CVE-2026-3549, GHSA-j2g5-52p7-mfpc, JLSEC-2026-708, UBUNTU-CVE-2026-3549.