VulnerabilityPublished 13 Jan 2026Updated 15 Jan 2026

CVE-2026-22818: honojs hono · Improper Verification of Cryptographic Signature

Affects honojs honoSource CVE Database V5

Not known to be exploited · CVSS 8.2 High : upgrade to 4.11.4 soon.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score

8.2High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 3% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 4.11.4

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: High
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 13 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade hono and honojs/hono to 4.11.4.

Affected software

Product	Affected	Fixed in
honojshono	Affected <4.11.4	Fixed in 4.11.4
npmhonojs/hono`pkg:npm/honojs/hono`Other threats	Affected <4.11.4	Fixed in 4.11.4

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

To mitigate CVE-2026-22818, organizations should immediately upgrade all Hono framework instances to version 4.11.4 or later, where the vulnerability is fixed. Developers must audit their JWT verification middleware configurations to ensure that algorithm validation does not rely on untrusted JWT header values and that an explicit allowlist of acceptable asymmetric algorithms is enforced. It is critical to review all applications using Hono for JWT authentication and verify that no custom overrides weaken signature verification. Implementing additional monitoring and alerting for suspicious JWT usage patterns can help detect exploitation attempts. Organizations should also conduct penetration testing focused on JWT authentication flows to identify any residual weaknesses. For environments where immediate upgrade is not feasible, consider deploying Web Application Firewalls (WAFs) with rules to detect and block malformed JWT tokens or unusual authentication requests. Finally, maintain an inventory of all applications using Hono to ensure comprehensive coverage of remediation efforts.

Description

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 algorithm specified in the JWT header to influence signature verification when the selected JWK did not explicitly define an algorithm. This could enable JWT algorithm confusion and, in certain configurations, allow forged tokens to be accepted. The JWK/JWKS JWT verification middleware has been updated to require an explicit allowlist of asymmetric algorithms when verifying tokens. The middleware no longer derives the verification algorithm from untrusted JWT header values. This vulnerability is fixed in 4.11.4.

Impact

The primary impact of CVE-2026-22818 is on the integrity of authentication and authorization mechanisms relying on JWT tokens in applications built with vulnerable versions of Hono. Attackers exploiting this flaw can forge JWT tokens, potentially gaining unauthorized access to protected resources, escalating privileges, or impersonating legitimate users. This can lead to data breaches, unauthorized transactions, and compromise of sensitive information. For European organizations, especially those in regulated industries such as finance, healthcare, and government, this vulnerability poses significant risks to compliance with data protection regulations like GDPR. The flaw does not directly affect availability or confidentiality but undermines trust in identity verification processes. Since the vulnerability can be exploited remotely without authentication or user interaction, it increases the attack surface for threat actors targeting European enterprises using Hono-based applications. The absence of known exploits in the wild currently reduces immediate risk but does not diminish the urgency for remediation given the high CVSS score and potential impact.

CWE-347Improper Verification of Cryptographic Signature (opens in a new tab)
Base weaknessOWASP Top 10 A04:2025: Cryptographic Failures (opens in a new tab)
The product does not verify, or incorrectly verifies, the cryptographic signature for data.
OWASP Cheat Sheets
XML Security (opens in a new tab)
REST Security (opens in a new tab)
JSON Web Token for Java (opens in a new tab)
REST Assessment (opens in a new tab)
Cross-Site Request Forgery Prevention (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.2 (opens in a new tab)
V3.5.3 (opens in a new tab)
V13.2.6 (opens in a new tab)
Attack patterns
Padding Oracle Crypto Attack (opens in a new tab)
Signature Spoofing by Improper Validation (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 21 Jan 2026, 02:20 UTC

WeaknessesCWE-347

Technical details

References

Community reviews

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