wolfSSL up to 5.9.0 wc_VerifyEccsiHash signature verification

CVSS Meta Temp Score
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CTI Interest Score
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3.6$0-$5k0.00

Summaryinfo

A vulnerability classified as problematic has been found in wolfSSL up to 5.9.0. Affected by this vulnerability is the function wc_VerifyEccsiHash. This manipulation causes signature verification. The identification of this vulnerability is CVE-2026-5466. It is possible to initiate the attack remotely. There is no exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability has been found in wolfSSL up to 5.9.0 and classified as problematic. Affected by this vulnerability is the function wc_VerifyEccsiHash. The manipulation with an unknown input leads to a signature verification vulnerability. The CWE definition for the vulnerability is CWE-347. The product does not verify, or incorrectly verifies, the cryptographic signature for data. As an impact it is known to affect integrity. The summary by CVE is:

wolfSSL's ECCSI signature verifier `wc_VerifyEccsiHash` decodes the `r` and `s` scalars from the signature blob via `mp_read_unsigned_bin` with no check that they lie in `[1, q-1]`. A crafted forged signature could verify against any message for any identity, using only publicly-known constants.

The weakness was shared by Calif.io In. It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-5466 since 04/03/2026. The exploitation appears to be difficult. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 305888 (Linux Distros Unpatched Vulnerability : CVE-2026-5466), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.9.1 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 (305888). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

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Version

License

Website

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: 3.7
VulDB Meta Temp Score: 3.6

VulDB Base Score: 3.7
VulDB Temp Score: 3.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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

Exploitinginfo

Class: Signature verification
CWE: CWE-347 / CWE-345
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: 305888
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-5466

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: wolfSSL 5.9.1
Patch: github.com

Timelineinfo

04/03/2026 CVE reserved
04/10/2026 +7 days Advisory disclosed
04/10/2026 +0 days VulDB entry created
04/12/2026 +2 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Researcher: Calif.io In
Status: Confirmed

CVE: CVE-2026-5466 (🔒)
GCVE (CVE): GCVE-0-2026-5466
GCVE (VulDB): GCVE-100-356719

Entryinfo

Created: 04/10/2026 06:25
Updated: 04/12/2026 08:04
Changes: 04/10/2026 06:25 (67), 04/12/2026 08:04 (2)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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