CVE-2026-48522— PyJWKClient: missing scheme allowlist enables SSRF + token forgery via file://, ftp://, data: schemes

PyJWKClient: missing scheme allowlist enables SSRF + token forgery via file://, ftp://, data: schemes

PyJWT is a JSON Web Token implementation in Python. Prior to 2.13.0, PyJWKClient passes its uri argument directly to urllib.request.urlopen() which uses Python stdlib's default OpenerDirector registering HTTPHandler, HTTPSHandler, FTPHandler, FileHandler, and DataHandler. There is currently no documented option to restrict which schemes PyJWKClient will fetch. If an application's jku URL ingestion path accepts attacker-influenced URLs (e.g., from JWT header, configuration file, OAuth flow parameter), the attacker can cause PyJWKClient to read arbitrary local files via file:// (SSRF on local filesystem), cause PyJWKClient to attempt FTP / data-URI fetches (broader SSRF surface), or forge tokens that PyJWT verifies as valid. The library does not directly return non-HTTP(S) URI contents to the attacker; the chained "plant a JWKS to forge tokens" scenario described in the original report requires additional application-layer flaws (attacker write access to a filesystem path, untrusted jku derivation) that this fix does not address. This vulnerability is fixed in 2.13.0.

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

未有动机的代理或中间人(混淆代理)

pyjwt 代码问题漏洞

pyjwt是美国José Padilla个人开发者的一个 Python 库。允许对 JSON Web 令牌（JWT）进行编码和解码。 PyJWT 2.13.0之前版本存在代码问题漏洞，该漏洞源于PyJWKClient直接将uri参数传递给urllib.request.urlopen()，使用Python标准库的默认OpenerDirector注册HTTPHandler、HTTPSHandler、FTPHandler、FileHandler和DataHandler，且未限制PyJWKClient可获取的方案

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