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NVD Vulnerability Details :

CVE-2026-3849

Analyzed

Source-facts@wolfssl.com

Published At-19 Mar, 2026 | 21:17

Updated At-26 Mar, 2026 | 18:20

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.

Date Added	Due Date	Vulnerability Name	Required Action
	N/A

Metrics

Type	Version	Base score	Base severity	Vector
Secondary	4.0	6.9	MEDIUM	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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:D/RE:M/U:Amber
Primary	3.1	9.8	CRITICAL	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Type: Secondary

Version: 4.0

Base score: 6.9

Base severity: 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:D/RE:M/U:Amber

Type: Primary

Version: 3.1

Base score: 9.8

Base severity: CRITICAL

Vector:

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CPE Matches

wolfssl>>wolfssl>>Versions from 5.6.0(inclusive) to 5.9.0(exclusive)

cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*

Weaknesses

CWE ID	Type	Source
CWE-787	Secondary	facts@wolfssl.com

CWE ID: CWE-787

Type: Secondary

Source: facts@wolfssl.com

References

Hyperlink	Source	Resource
https://github.com/wolfSSL/wolfssl/pull/9737	facts@wolfssl.com	Issue Tracking Patch

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

Source: facts@wolfssl.com

Resource:

Issue Tracking

Patch

CISA Catalog

Metrics

CPE Matches

Weaknesses

Evaluator Description

Evaluator Impact

Evaluator Solution

Vendor Statements

References

Change History