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CVE-2026-75866— Punk::OAuth2::Server versions through 0.03 for Perl issue access tokens outside a client's registered scopes and grant types because no authorization path reads them

Quick assessment

Affected
CVE-2026-75866
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Punk::OAuth2::Server（Perl 模块，版本 0.03 及更早版本）存在漏洞，允许访问令牌（access tokens）超出客户端已注册的 scopes（权限范围）和 grant_types（授权类型），原因是缺乏对这些字段的有效授权路径校验。 在 Punk::OAuth2::Server::Store 中，每个客户端的 scopes 和 grant_types 均被分别注册，并在客户端注册信息中予以记录。令牌分发逻辑基于请求体中的 grant_type 进行，因此，一个仅注册了 authoriz

AI Predicted 9.8 Difficulty: Easy EPSS 0.20% · P10

Possible ATT&CK Techniques 1 AI

T1078 · Valid Accounts

Affected Version Matrix 1

VendorProduct Version RangeStatus
None None ≤ 0.03 affected

I. Basic Information for CVE-2026-75866

Vulnerability Information
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Vulnerability Title
Punk::OAuth2::Server versions through 0.03 for Perl issue access tokens outside a client's registered scopes and grant types because no authorization path reads them
Source: CVE Program / CVE List V5
Vulnerability Description
Punk::OAuth2::Server versions through 0.03 for Perl issue access tokens outside a client's registered scopes and grant types because no authorization path reads them. Punk::OAuth2::Server::Store registers scopes and grant_types per client and documents both as client registration. token dispatches on the grant_type in the request body, so a client registered for authorization_code alone can ask for client_credentials, and that arm passes the requested scope straight to the minter, which signs it into the at+jwt access token. authorize copies the query scope into the authorization code record without comparing it against the registration, leaving the optional consent hook as the only check between an arbitrary scope and the issued code. redirect_uris on the same client row is read and enforced. A registered client can obtain a correctly signed token carrying any scope it names, and a resource server running Punk::OAuth2::Checker accepts that token and honours the scope. A client registered without a secret authenticates on its client_id alone, so anyone who knows that identifier can request one.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
授权机制缺失
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
- - 0 ~ 0.03 -

II. Public POCs for CVE-2026-75866

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III. Intelligence Information for CVE-2026-75866

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Patches & Fixes for CVE-2026-75866 (1)

Other References for CVE-2026-75866 (1)

IV. Related Vulnerabilities

Same weakness: CWE-862

V. Comments for CVE-2026-75866

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