What is the CVSS score of CVE-2026-22817?

CVE-2026-22817 has a CVSS 3.1 base score of 8.2 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N. EPSS exploitation probability: 0.0%.

How to fix or mitigate CVE-2026-22817?

Within 7 days: Identify all affected systems and apply vendor patches promptly. Vendor patch is available.

Hono CVE-2026-22817

HIGH

Improper Verification of Cryptographic Signature (CWE-347)

2026-01-13 security-advisories@github.com

GHSA-f67f-6cw9-8mq4

Information Disclosure Hono

8.2

CVSS 3.1 · GitHub Advisory

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Craft JWT with unspecified alg header
Delivery

Submit to Hono JWT middleware
Exploit

Middleware derives algorithm from JWK
Execution

Accept forged token
Impact

Bypass authentication

Vulnerability Assessment

Weakness	CWE CWE-347 OWASP Top 10:2025 A04:2025 - Cryptographic Failures ASVS 5.0 V11 - Cryptography Signature verification
Exploitation Conditions	Hono versions prior to 4.11.4 with JWT middleware using JWK/JWKS where the alg option is not explicitly specified in configuration. No authentication required for remote exploitation.
Impact	CVSS 8.2 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: None. User interaction: None.
Exploit ScenarioDerived	An attacker could exploit this vulnerability to JWT algorithm confusion and, in certain configurations, allow forged tokens to b.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Hono before version 4.11.4 contains a JWT algorithm confusion vulnerability in its JWK/JWKS verification middleware that allows attackers to forge authentication tokens when the JWK lacks explicit algorithm specification. An unauthenticated remote attacker can exploit this by manipulating the JWT header's alg value to bypass signature verification in affected configurations. The vulnerability is resolved in version 4.11.4, which now requires explicit algorithm specification to prevent header-driven algorithm confusion.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 21:54 CVSS 8.2

Hono versions up to 4.11.4 is affected by improper verification of cryptographic signature (CVSS 8.2).

RemediationAI

A vendor patch is available — apply it immediately. Fixed in version 4.11.4.. Restrict network access to the affected service where possible.

Affected Packages

npm hono fix: 4.11.4

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in npm

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability (CWE-347: Improper Verification of Cryptographic Signature) affects Hono. Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.11.4, there is a flaw in Hono’s JWK/JWKS JWT verification middleware allowed the JWT header’s alg value to influence signature verification when the selected JWK did not explicitly specify an algorithm. This could enable JWT algorithm confusion and, in certain configurations, allow forged tokens to be accepted. As part of this fix, the JWT middleware now requires the alg option to be explicitly speci

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

GitHub Advisory PRIMARY 8.2 HIGH

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

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

High

Availability

None

Lifecycle Timeline

Patch released

Jan 20, 2026 - 16:48 nvd

Patch available

CVE Published

Jan 13, 2026 - 20:16 nvd

HIGH 8.2

DescriptionGitHub Advisory

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.11.4, there is a flaw in Hono’s JWK/JWKS JWT verification middleware allowed the JWT header’s alg value to influence signature verification when the selected JWK did not explicitly specify an algorithm. This could enable JWT algorithm confusion and, in certain configurations, allow forged tokens to be accepted. As part of this fix, the JWT middleware now requires the alg option to be explicitly specified. This prevents algorithm confusion by ensuring that the verification algorithm is not derived from untrusted JWT header values. This vulnerability is fixed in 4.11.4.

Executive ViewAI

Why It Matters

Organizations using Hono face notable risk from CVE-2026-22817, a signature bypass vulnerability rated CVSS 8.2. Successful exploitation could significantly impact the confidentiality, integrity, or availability of affected systems. A patch is available and should be applied as part of regular vulnerability management.

Business Impact: High

Compensating Controls

Apply vendor patch. If immediate patching is not feasible: (1) Implement network-level access controls to limit exposure; (2) Enable enhanced monitoring and alerting; (3) Apply principle of least privilege.

Threat Intelligence Overview

EPSS Score

0.0%

Top 96% exploitable

Data Quality

4 sources

Confidence: Medium

NVD

CVE.org

EPSS

GitHub

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC No

EPSS 0.0%

Patch available Yes

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Yes

Human Impact

High

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +41

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.