by Kastro
Paper/Archive/CVE-2026-3849

CVE-2026-3849

wolfSSL Inc. wolfSSL — Buffer Overflow in HPKE via Oversized ECH Config

EPSS 0.5%CVSS 9.8
critical.is priorityof 100
37
CVSS 9.8 (NVD)9.8 / 10 × 3029.4Not in CISA KEV+300.0EPSS percentile 39.2.392 × 207.8No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
wolfSSLv5.6.0-stable – v5.8.4-stable–CNA

Scores by source

NVD9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
wolfSSL (CNA)6.9CVSS: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
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: partial

References

refgithub.com/wolfSSL/wolfssl/pull/9737