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CVE-2023-48223— fast-jwt JWT Algorithm Confusion

Quick assessment

Affected
nearform fast-jwt
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.

fast-jwt是更快的JSON Web Token实现。 fast-jwt 3.3.2之前版本存在安全漏洞，该漏洞源于无法正确匹配公钥的所有常见 PEM 格式。

CVSS 5.9 · Medium EPSS 0.68% · P51
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I. Basic Information for CVE-2023-48223

Vulnerability Information
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Vulnerability Title
fast-jwt JWT Algorithm Confusion
Source: CVE Program / CVE List V5
Vulnerability Description
fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to version 3.3.2, the fast-jwt library does not properly prevent JWT algorithm confusion for all public key types. The 'publicKeyPemMatcher' in 'fast-jwt/src/crypto.js' does not properly match all common PEM formats for public keys. To exploit this vulnerability, an attacker needs to craft a malicious JWT token containing the HS256 algorithm, signed with the public RSA key of the victim application. This attack will only work if the victim application utilizes a public key containing the `BEGIN RSA PUBLIC KEY` header. Applications using the RS256 algorithm, a public key with a `BEGIN RSA PUBLIC KEY` header, and calling the verify function without explicitly providing an algorithm, are vulnerable to this algorithm confusion attack which allows attackers to sign arbitrary payloads which will be accepted by the verifier. Version 3.3.2 contains a patch for this issue. As a workaround, change line 29 of `blob/master/src/crypto.js` to include a regular expression.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
输入验证不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
fast-jwt 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
fast-jwt是更快的JSON Web Token实现。 fast-jwt 3.3.2之前版本存在安全漏洞，该漏洞源于无法正确匹配公钥的所有常见 PEM 格式。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
nearform fast-jwt < 3.3.2 -

II. Public POCs for CVE-2023-48223

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III. Intelligence Information for CVE-2023-48223

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Vendor Advisories for CVE-2023-48223 (1)

Other References for CVE-2023-48223 (1)

IV. Related Vulnerabilities

Same product: fast-jwt
Same vendor: nearform
Same weakness: CWE-20

V. Comments for CVE-2023-48223

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