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CVE-2026-102265— PyJWT: Uncaught RecursionError in jwt.decode() on deeply nested token header

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 JSON Web Token（JWT）标准的 Python 实现。在版本 2.13.0 至 2.14.0 之间， 中的 方法存在漏洞，因为其异常处理仅捕获了 ，而未捕获 。当令牌头部的嵌套层级过深并传递给 时，便会触发递归错误。由于 未被正确捕获，它绕过了 PyJWT 文档中定义的异常处理体系，导致未认证的畸形令牌可引发请求级故障，并返回 HTTP 500 错误。该问题已在版本 2.14.0 中得到修复。

CVSS 5.3 · Medium

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-102265

Vulnerability Information
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Vulnerability Title
PyJWT: Uncaught RecursionError in jwt.decode() on deeply nested token header
Source: CVE Program / CVE List V5
Vulnerability Description
PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, PyJWS._load in jwt/api_jws.py is affected because parser catches ValueError but not RecursionError. This occurs when a deeply nested token header reaches json.loads. As a result, RecursionError escapes the documented PyJWT error hierarchy. Consequently, an unauthenticated malformed token can cause a request-level failure and HTTP 500. This issue is fixed in version 2.14.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
未经控制的递归
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
jpadilla pyjwt >= 2.13.0, < 2.14.0 -

II. Public POCs for CVE-2026-102265

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III. Intelligence Information for CVE-2026-102265

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Other References for CVE-2026-102265 (3)

Same Patch Batch · jpadilla · 2026-09-28 · 13 CVEs total

CVE-2026-102268 9.1 CRITICAL PyJWT: Asymmetric-PEM detection bypass: whitespace/line-ending-mutated public keys skip th
CVE-2026-102266 7.4 HIGH PyJWK accepts empty HMAC keys, bypassing PyJWT's empty-key validation
CVE-2026-102267 7.4 HIGH PyJWT: PyJWKClient follows redirects when fetching JWKS
CVE-2026-102271 7.4 HIGH PyJWT: Public keys in DER form are accepted as HMAC secrets, bypassing the CVE-2022-29217
CVE-2026-102272 7.4 HIGH PyJWT BOM Bypass
CVE-2026-102273 7.4 HIGH PyJWT accepts public JWK containers as HMAC secrets
CVE-2026-102275 6.5 MEDIUM PyJWT accepts inconsistent OKP x/d JWKs, causing public/private key identity confusion
CVE-2026-102274 5.9 MEDIUM PyJWT: Malformed RSA JWK aborts parsing of an entire JWK Set
CVE-2026-101918 5.3 MEDIUM PyJWT: Unauthenticated RecursionError DoS in pre-verification payload parse (PyJWKClient.g
CVE-2026-101917 5.3 MEDIUM PyJWT: PyJWKClient still amplifies unauthenticated JWKS fetches on unknown kid values (inc
CVE-2026-102269 4.8 MEDIUM PyJWT: Non-canonical signature segments enable raw-token revocation bypass
CVE-2026-102270 4.4 MEDIUM PyJWT: ReDoS vulnerability when calling the `is_pem_format` function.

IV. Related Vulnerabilities

Same product: pyjwt
Same vendor: jpadilla
Same weakness: CWE-674

V. Comments for CVE-2026-102265

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