VDB-351794 · CVE-2026-3849 · Nessus 303183

wolfSSL up to 5.8.4 ECH wc_HpkeLabeledExtract out-of-bounds write

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8.4	$0-$5k	0.00

Summaryinfo

A vulnerability, which was classified as critical, was found in wolfSSL up to 5.8.4. This vulnerability affects the function wc_HpkeLabeledExtract of the component ECH Handler. Such manipulation leads to out-of-bounds write. This vulnerability is traded as CVE-2026-3849. The attack may be launched remotely. There is no exploit available. A patch should be applied to remediate this issue.

Detailsinfo

A vulnerability, which was classified as critical, has been found in wolfSSL up to 5.8.4. Affected by this issue is the function wc_HpkeLabeledExtract of the component ECH Handler. The manipulation with an unknown input leads to a out-of-bounds write vulnerability. Using CWE to declare the problem leads to CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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 weakness was shared by Haruto Kimura. The advisory is available at github.com. This vulnerability is handled as CVE-2026-3849 since 03/09/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 303183 (Linux Distros Unpatched Vulnerability : CVE-2026-3849), which helps to determine the existence of the flaw in a target environment.

Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com.

The vulnerability is also documented in the vulnerability database at Tenable (303183). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Name

wolfSSL

Version

License

open-source

Website

Product: https://github.com/wolfSSL/wolfssl/

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 8.5
VulDB Meta Temp Score: 8.4

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 9.8
NVD Vector: 🔒

CVSSv2info

AV	AC	Au	C	I	A
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💳	💳	💳	💳	💳	💳
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Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Out-of-bounds write
CWE: CWE-787 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 303183
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-3849

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

0-Day Time: 🔒

Patch: github.com

Timelineinfo

03/09/2026 CVE reserved
03/20/2026 +11 days Advisory disclosed
03/20/2026 +0 days VulDB entry created
03/26/2026 +6 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Researcher: Haruto Kimura
Status: Confirmed

CVE: CVE-2026-3849 (🔒)
GCVE (CVE): GCVE-0-2026-3849
GCVE (VulDB): GCVE-100-351794

Entryinfo

Created: 03/20/2026 07:09
Updated: 03/26/2026 19:54
Changes: 03/20/2026 07:09 (71), 03/23/2026 16:50 (2), 03/24/2026 15:12 (1), 03/26/2026 19:54 (11)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.