How severe is CVE-2026-22818?

CVE-2026-22818 has a CVSS 3.x base score of 8.2, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity high, and availability none.

Is CVE-2026-22818 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (2nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-22818?

CVE-2026-22818 affects Hono. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-22818?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-22818 have an EU (EUVD) identifier?

Yes. CVE-2026-22818 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-2017.

When was CVE-2026-22818 published?

CVE-2026-22818 was published on 2026-01-13 and last updated on 2026-06-17.

CVE-2026-22818

CVE-2026-22818 is a high-severity vulnerability in Hono with a CVSS 3.x base score of 8.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-347.

Key facts

Severity: High (CVSS 3.x base score 8.2)
EPSS exploit prediction: 0% (2nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-2017
Weakness: CWE-347
Affected product: Hono
Published: 2026-01-13
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-22818?: 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.
How severe is CVE-2026-22818?: CVE-2026-22818 has a CVSS 3.x base score of 8.2, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity high, and availability none.
Is CVE-2026-22818 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (2nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-22818?: CVE-2026-22818 affects Hono. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-22818?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-22818 have an EU (EUVD) identifier?: Yes. CVE-2026-22818 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-2017.
When was CVE-2026-22818 published?: CVE-2026-22818 was published on 2026-01-13 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:hono:hono:*:*:*:*:*:node.js:*:*

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