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CVE-2026-102269— PyJWT: Non-canonical signature segments enable raw-token revocation bypass

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 是基于 JSON Web Token（JWT）标准的 Python 实现。在版本 2.14.0 之前，PyJWT 的签名段存在安全隐患：签名段解码过程允许接收超出标准 Base64URL 编码规范的字符。具体而言，当向一个合法的紧凑型 JWS（JSON Web Signature）签名段末尾附加非 Base64URL 规范的字符时，就会触发此问题。 其后果是，base64url_decode 函数会为不同序列化形式的签名段生成相同的签名字节。因此，在对原始令牌进行撤销检查时，系统可能无法识别出经过等价修

CVSS 4.8 · Medium

Possible ATT&CK Techniques 1 AI

T1550 · Use Alternate Authentication Material
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I. Basic Information for CVE-2026-102269

Vulnerability Information
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Vulnerability Title
PyJWT: Non-canonical signature segments enable raw-token revocation bypass
Source: CVE Program / CVE List V5
Vulnerability Description
PyJWT is a Python implementation of JSON Web Token standards. Prior to 2.14.0, PyJWT signature segment is affected because signature segment decoding accepts characters outside the canonical Base64URL representation. This occurs when non-Base64URL characters are appended to a valid compact JWS signature segment. As a result, base64url_decode produces the same signature bytes for different serialized segments. Consequently, raw-token revocation checks can fail to recognize an equivalent modified token. This issue is fixed in version 2.14.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
不正确的行为次序：规范化之前验证
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
jpadilla pyjwt < 2.14.0 -

II. Public POCs for CVE-2026-102269

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III. Intelligence Information for CVE-2026-102269

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Other References for CVE-2026-102269 (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-2026-102265 5.3 MEDIUM PyJWT: Uncaught RecursionError in jwt.decode() on deeply nested token header
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-180

V. Comments for CVE-2026-102269

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