wolfSSL up to 5.8.x ALPN Parser out-of-bounds

CVSS Meta Temp Score
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CTI Interest Score
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6.3$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as problematic, has been found in wolfSSL up to 5.8.x. This issue affects some unknown processing of the component ALPN Parser. The manipulation leads to out-of-bounds. This vulnerability is referenced as CVE-2026-3547. Remote exploitation of the attack is possible. No exploit is available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in wolfSSL up to 5.8.x and classified as problematic. This issue affects an unknown functionality of the component ALPN Parser. The manipulation with an unknown input leads to a out-of-bounds vulnerability. Using CWE to declare the problem leads to CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. Impacted is availability. The summary by CVE is:

Out-of-bounds read in ALPN parsing due to incomplete validation. wolfSSL 5.8.4 and earlier contained an out-of-bounds read in ALPN handling when built with ALPN enabled (HAVE_ALPN / --enable-alpn). A crafted ALPN protocol list could trigger an out-of-bounds read, leading to a potential process crash (denial of service). Note that ALPN is disabled by default, but is enabled for these 3rd party compatibility features: enable-apachehttpd, enable-bind, enable-curl, enable-haproxy, enable-hitch, enable-lighty, enable-jni, enable-nginx, enable-quic.

The weakness was published by Oleh Konko. The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-3547 since 03/04/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Neither technical details nor an exploit are publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 303179 (Linux Distros Unpatched Vulnerability : CVE-2026-3547), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.9.0 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (303179). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.4
VulDB Meta Temp Score: 6.3

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.5
CNA Vector (wolfSSL): 🔒

CVSSv2info

AVACAuCIA
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Out-of-bounds
CWE: CWE-125 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 303179
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-3547

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: wolfSSL 5.9.0
Patch: github.com

Timelineinfo

03/04/2026 CVE reserved
03/20/2026 +16 days Advisory disclosed
03/20/2026 +0 days VulDB entry created
03/24/2026 +4 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Researcher: Oleh Konko
Status: Confirmed

CVE: CVE-2026-3547 (🔒)
GCVE (CVE): GCVE-0-2026-3547
GCVE (VulDB): GCVE-100-351905

Entryinfo

Created: 03/20/2026 08:00
Updated: 03/24/2026 13:12
Changes: 03/20/2026 08:00 (65), 03/23/2026 16:50 (2), 03/24/2026 13:12 (1)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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