CVE-2026-101918— PyJWT: Unauthenticated RecursionError DoS in pre-verification payload parse (PyJWKClient.get_signing_key_from_jwt / verify_signature=False)
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 标准的 Python 实现。在版本 2.0.0a1 至 2.15.0 期间， 方法存在缺陷，因为其负载（payload）解析器捕获了 异常，但未捕获 （递归错误）。当攻击者控制的递归嵌套负载传入 时，会引发递归错误。由于文档中描述的 PyJWT 异常处理机制并未涵盖此失败场景，因此未经身份验证的请求可能触发异常，并导致返回 HTTP 500 服务器内部错误响应。 该漏洞公告所指出的受影响实现还包括 中设置 的情况。此问题已在版本 2.15.0 中修复。
Possible ATT&CK Techniques 1 AI
T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-101918
Vulnerability Information
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Vulnerability Title
PyJWT: Unauthenticated RecursionError DoS in pre-verification payload parse (PyJWKClient.get_signing_key_from_jwt / verify_signature=False)
Source: CVE Program / CVE List V5
Vulnerability Description
PyJWT is a Python implementation of JSON Web Token standards. From 2.0.0a1 until 2.15.0, PyJWT PyJWKClient.get_signing_key_from_jwt is affected because payload parser catches ValueError but not RecursionError. This occurs when an attacker-controlled recursively nested payload reaches json.loads. As a result, documented PyJWT exception handling does not contain the failure. Consequently, an unauthenticated request can raise an exception that may produce an HTTP 500 response. The advisory-defined affected implementation also includes jwt/api_jwt.py, verify_signature=False. This issue is fixed in version 2.15.0.
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
未捕获的异常
Source: CVE Program / CVE List V5
Affected Products
II. Public POCs for CVE-2026-101918
| # | POC Description | Source Link | Shenlong Link |
|---|
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Other References for CVE-2026-101918 (3)
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https://github.com/jpadilla/pyjwt/releases/tag/2.15.0 x_refsource_MISC
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https://github.com/jpadilla/pyjwt/security/advisories/GHSA-42vr-xj54-vc7v x_refsource_CONFIRM
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-2026-101917 | 5.3 MEDIUM | PyJWT: PyJWKClient still amplifies unauthenticated JWKS fetches on unknown kid values (inc |
| CVE-2026-102265 | 5.3 MEDIUM | PyJWT: Uncaught RecursionError in jwt.decode() on deeply nested token header |
| 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
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CVE-2026-102265
PyJWT: Uncaught RecursionError in jwt.decode() on deeply nes -
CVE-2026-102275
PyJWT accepts inconsistent OKP x/d JWKs, causing public/priv -
CVE-2026-102274
PyJWT: Malformed RSA JWK aborts parsing of an entire JWK Set -
CVE-2026-102273
PyJWT accepts public JWK containers as HMAC secrets -
CVE-2026-102272
PyJWT BOM Bypass
Same vendor: jpadilla
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CVE-2026-102265
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CVE-2026-102275
PyJWT accepts inconsistent OKP x/d JWKs, causing public/priv -
CVE-2026-102274
PyJWT: Malformed RSA JWK aborts parsing of an entire JWK Set -
CVE-2026-102273
PyJWT accepts public JWK containers as HMAC secrets -
CVE-2026-102272
PyJWT BOM Bypass
Same weakness: CWE-248
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V. Comments for CVE-2026-101918
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