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CVE-2026-48524— PyJWT: PyJWKClient unbounded JWKS endpoint requests via attacker-controlled kid values (DoS)

Quick assessment

Affected
jpadilla pyjwt
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.

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之前版本存在安全漏洞，该漏洞源于PyJWKClient.get_signing_key()对每个具有未知kid值的JWT强制向JWKS端点发起新的HTTP请求，且无速率限制，导致攻击者可以触发无限制的出站请求。

CVSS 3.7 · Low EPSS 0.32% · P23

Affected Version Matrix 1

VendorProduct Version RangeStatus
jpadilla pyjwt < 2.13.0 affected
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I. Basic Information for CVE-2026-48524

Vulnerability Information
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Vulnerability Title
PyJWT: PyJWKClient unbounded JWKS endpoint requests via attacker-controlled kid values (DoS)
Source: CVE Program / CVE List V5
Vulnerability Description
PyJWT is a JSON Web Token implementation in Python. Prior to 2.13.0, PyJWKClient.get_signing_key() forces a fresh HTTP request to the JWKS endpoint for every JWT with an unknown kid value, with no rate limiting. Since kid comes from the unverified token header, an attacker can trigger unlimited outbound requests. The vulnerability surfaces only when a JWKS fetch fails; an attacker can attempt to provoke that with sustained unknown-kid traffic, but the outcome depends on upstream JWKS-endpoint behavior (rate limiting, transient errors) which is beyond the attacker's control. This vulnerability is fixed in 2.13.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
抛出异常的清理不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
pyjwt 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
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之前版本存在安全漏洞，该漏洞源于PyJWKClient.get_signing_key()对每个具有未知kid值的JWT强制向JWKS端点发起新的HTTP请求，且无速率限制，导致攻击者可以触发无限制的出站请求。
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
jpadilla pyjwt < 2.13.0 -

II. Public POCs for CVE-2026-48524

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III. Intelligence Information for CVE-2026-48524

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Vendor Advisories for CVE-2026-48524 (1)

Same Patch Batch · jpadilla · 2026-05-28 · 5 CVEs total

CVE-2026-48526 7.4 HIGH PyJWT: Public-key JWK accepted as HMAC secret enables forged HS256 tokens when mixed famil
CVE-2026-48523 5.4 MEDIUM PyJWT: Algorithm allow-list bypass when decoding with `PyJWK` / `PyJWKClient` keys
CVE-2026-48525 5.3 MEDIUM PyJWT: Unauthenticated DoS via unbounded Base64URL decoding of unused payload segment in b
CVE-2026-48522 4.2 MEDIUM PyJWKClient: missing scheme allowlist enables SSRF + token forgery via file://, ftp://, da

IV. Related Vulnerabilities

Same product: pyjwt
Same vendor: jpadilla
Same weakness: CWE-460

V. Comments for CVE-2026-48524

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