CVE-2026-3849CWE-787

Buffer Overflow in HPKE via Oversized ECH Config

Medium · published March 19, 2026

CVSS v4.0
6.9
EPSS
1%
Percentile
56.0
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
6.9 · MEDIUM
Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/V:D/RE:M/U:Amber
EPSS
0.00794 · 56.0th percentile
Weakness
CWE-787 · Out-of-bounds Write
Published
2026-03-19T20:29Z
EPSS history
Timeline
  • 19 MAR 20:29Z
    Buffer Overflow in HPKE via Oversized ECH Config
    cvelistv5