Stack Buffer Overflow in wolfSSL 5.8.4 ECH Support
CVE-2026-3849

6.9MEDIUM

Key Information:

Vendor

Wolfssl Inc.

Status
Wolfssl
Vendor
CVE Published:
19 March 2026

What is CVE-2026-3849?

A stack buffer overflow vulnerability exists in wolfSSL 5.8.4 related to Encrypted Client Hello (ECH) support. When a maliciously crafted ECH configuration is processed, it can trigger a buffer overflow on the client side. This may lead to unexpected program crashes and could potentially allow remote execution of arbitrary code, exposing systems using the affected component. Note that ECH support is disabled by default and requires explicit enabling through configuration to be at risk.

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Affected Version(s)

wolfSSL v5.6.0-stable

References

https://github.com/wolfSSL/wolfssl/pull/9737

CVSS V4

Score:
6.9
Severity:
MEDIUM
Confidentiality:
None
Integrity:
Low
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Haruto Kimura (Stella)
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