Hono: JWT middleware accepts any Authorization scheme, not only Bearer

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.21, the jwt and jwk middlewares do not verify that the Authorization header value uses theBearer scheme. Any two-part header value — regardless of the scheme name in the first position — proceeds to JWT verification. A request presenting a valid JWT under a non-Bearer scheme identifier (such as Basic or Token) is authenticated identically to a correctly formed Bearer request. This vulnerability is fixed in 4.12.21.

Source published

28 May 2026 15:29:44 UTC

Source modified

30 May 2026 01:59:15 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 4.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.21, the jwt and jwk middlewares do not verify that the Authorization header value uses theBearer scheme. Any two-part header value — regardless of the scheme name in the first position — proceeds to JWT verification. A request presenting a valid JWT under a non-Bearer scheme identifier (such as Basic or Token) is authenticated identically to a correctly formed Bearer request. This vulnerability is fixed in 4.12.21.

Source published

May 28, 2026, 3:29:44 PM (timezone not stated)

Source modified

May 30, 2026, 1:59:15 AM (timezone not stated)

Observed here

9 Nov 2026 12:02:49 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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EUVD CVSS 3.1 · 4.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.21, the jwt and jwk middlewares do not verify that the Authorization header value uses theBearer scheme. Any two-part header value — regardless of the scheme name in the first position — proceeds to JWT verification. A request presenting a valid JWT under a non-Bearer scheme identifier (such as Basic or Token) is authenticated identically to a correctly formed Bearer request. This vulnerability is fixed in 4.12.21.

Source published

28 May 2026 17:16:32 UTC

Source modified

14 Oct 2026 20:10:00 UTC

Observed here

25 Oct 2026 12:17:26 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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CVSS 3.1 · [email protected] · Secondary · 4.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

CVSS 3.1 · [email protected] · Primary · 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

### Summary The `jwt` and `jwk` middlewares do not verify that the `Authorization` header value uses the`Bearer` scheme. Any two-part header value — regardless of the scheme name in the first position — proceeds to JWT verification. A request presenting a valid JWT under a non-`Bearer` scheme identifier (such as `Basic` or `Token`) is authenticated identically to a correctly formed `Bearer` request. ### Details When processing an `Authorization` (or custom) header, the middleware splits the value on whitespace and uses the second token as the JWT to verify. It does not check that the first token is `bearer` (case-insensitively). RFC 6750 specifies that JWT bearer tokens must be presented using the `Bearer` scheme; other scheme identifiers carry distinct semantics and may be subject to different policies in network-layer security controls. This discrepancy means that scheme-aware external controls — such as WAF rules, API gateways, or reverse proxies that apply policies specific to the `Bearer` scheme identifier — can be bypassed by presenting a valid JWT under a different scheme name. This issue affects `hono/jwt` and `hono/jwk` middleware. ### Impact An attacker who possesses a valid JWT may present it under a non-`Bearer` scheme identifier and still pass middleware authentication. This may lead to: - Bypass of network-layer security controls that inspect or filter requests based on the authorization scheme identifier - Token reuse across authentication schemes in applications that use multiple authorization mechanisms This issue affects applications where `hono/jwt` or `hono/jwk` authentication is combined with external controls that enforce scheme-based access policies.

Source published

4 Jun 2026 17:52:04 UTC

Source modified

10 Sep 2026 03:50:49 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

Publisher rating · MODERATE