Hono Improperly Authorizes JWT Audience Validation

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Hono is a Web application framework that provides support for any JavaScript runtime. In versions from 1.1.0 to before 4.10.2, Hono’s JWT Auth Middleware does not provide a built-in aud (Audience) verification option, which can cause confused-deputy / token-mix-up issues: an API may accept a valid token that was issued for a different audience (e.g., another service) when multiple services share the same issuer/keys. This can lead to unintended cross-service access. Hono’s docs list verification options for iss/nbf/iat/exp only, with no aud support; RFC 7519 requires that when an aud claim is present, tokens MUST be rejected unless the processing party identifies itself in that claim. This issue has been patched in version 4.10.2.

Source published

22 Oct 2025 19:24:08 UTC

Source modified

23 Oct 2025 17:31:49 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 8.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

Hono is a Web application framework that provides support for any JavaScript runtime. In versions from 1.1.0 to before 4.10.2, Hono’s JWT Auth Middleware does not provide a built-in aud (Audience) verification option, which can cause confused-deputy / token-mix-up issues: an API may accept a valid token that was issued for a different audience (e.g., another service) when multiple services share the same issuer/keys. This can lead to unintended cross-service access. Hono’s docs list verification options for iss/nbf/iat/exp only, with no aud support; RFC 7519 requires that when an aud claim is present, tokens MUST be rejected unless the processing party identifies itself in that claim. This issue has been patched in version 4.10.2.

Source published

Oct 22, 2025, 7:24:08 PM (timezone not stated)

Source modified

Oct 23, 2025, 5:31:49 PM (timezone not stated)

Observed here

11 Nov 2026 04:30:31 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 8.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

Hono is a Web application framework that provides support for any JavaScript runtime. In versions from 1.1.0 to before 4.10.2, Hono’s JWT Auth Middleware does not provide a built-in aud (Audience) verification option, which can cause confused-deputy / token-mix-up issues: an API may accept a valid token that was issued for a different audience (e.g., another service) when multiple services share the same issuer/keys. This can lead to unintended cross-service access. Hono’s docs list verification options for iss/nbf/iat/exp only, with no aud support; RFC 7519 requires that when an aud claim is present, tokens MUST be rejected unless the processing party identifies itself in that claim. This issue has been patched in version 4.10.2.

Source published

22 Oct 2025 20:15:38 UTC

Source modified

8 Oct 2026 11:10:00 UTC

Observed here

25 Oct 2026 03:17:29 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 8.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

### Improper Authorization in Hono (JWT Audience Validation) Hono’s JWT authentication middleware did not validate the `aud` (Audience) claim by default. As a result, applications using the middleware without an explicit audience check could accept tokens intended for other audiences, leading to potential cross-service access (token mix-up). The issue is addressed by adding a new `verification.aud` configuration option to allow RFC 7519–compliant audience validation. This change is classified as a **security hardening improvement**, but the lack of validation can still be considered a vulnerability in deployments that rely on default JWT verification. ### Recommended secure configuration You can enable RFC 7519–compliant audience validation using the new `verification.aud` option: ```ts import { Hono } from 'hono' import { jwt } from 'hono/jwt' const app = new Hono() app.use( '/api/*', jwt({ secret: 'my-secret', verification: { // Require this API to only accept tokens with aud = 'service-a' aud: 'service-a', }, }) ) ``` Below is the original description by the reporter. For security reasons, it does not include PoC reproduction steps, as the vulnerability can be clearly understood from the technical description. --- ## The original description by the reporter ### Summary Hono’s **JWT Auth Middleware does not provide a built-in `aud` (Audience) verification option**, which can cause **confused-deputy / token-mix-up** issues: an API may accept a valid token that was **issued for a different audience** (e.g., another service) when multiple services share the same issuer/keys. This can lead to unintended cross-service access. Hono’s docs list verification options for `iss/nbf/iat/exp` only, with **no `aud` support**; RFC 7519 requires that when an `aud` claim is present, tokens **MUST** be rejected unless the processing party identifies itself in that claim. **Note:** This problem likely exists in the **JWK/JWKS-based middleware** as well (e.g., `jwk` / `verifyWithJwks`) ### Details - The middleware’s `verifyOptions` enumerate only `iss`, `nbf`, `iat`, and `exp`; there is **no `aud` option**. The same omission appears in the JWT Helper’s “Payload Validation” list. Developers relying on the middleware for complete standards-aligned validation therefore won’t check audience by default. - **Standards requirement:** RFC 7519 §4.1.3 states that each principal intended to process the JWT **MUST** identify itself with a value in the `aud` claim; if it does not, the JWT **MUST** be rejected (when `aud` is present). Lack of a first-class `aud` check increases the risk that tokens issued for **Service B** are accepted by **Service A**. - **Real-world effect:** In deployments with a single IdP/JWKS and shared keys across multiple services, a token minted for one audience can be mistakenly accepted by another audience unless developers implement a custom audience check. - For example, with Google Identity (OIDC), iss is always https://accounts.google.com (shared across apps), but aud differs per application because it is that app’s OAuth client ID; therefore, an attacker can host a separate service that supports “Sign in with Google,” obtain a valid ID token (JWT) for the victim user, and—if your API does not verify aud—use that token to access your API with the victim’s privileges. ### Impact **Type:** Authentication/authorization weakness via **token mix-up (confused-deputy)**. **Who is impacted:** Any Hono user who: - shares an issuer/keys across multiple services (common with a single IdP/JWKS) - distinguishes tokens by intended recipient using `aud`. **What can happen:** - **Cross-service access:** A token for *Service B* may be accepted by *Service A*. - **Boundary erosion:** ID tokens and access tokens, or separate API audiences, can be inadvertently intermixed. - This may causes unauthorized invocation of sensitive endpoints. **Recommended remediation:** 1) Add `verifyOptions.aud` (`string | string[] | RegExp`) to the middleware and enforce RFC 7519 semantics: In [verify method](https://github.com/honojs/hono/blob/db764c2f1d8a2905d66c78c41aa47e47d3a4165d/src/utils/jwt/jwt.ts#L99-L156), if `aud` is present and does not match with specified audiences, reject. 2) Ensure equivalent `aud` handling exists in the JWK/JWKS flow (`jwk` middleware / `verifyWithJwks`) so users of external IdPs can enforce audience consistently.

Source published

22 Oct 2025 15:21:18 UTC

Source modified

10 Sep 2026 03:50:30 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

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

Publisher rating · HIGH