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CVE-2026-119284— joserfc: Compact JWS size guard allocates attacker-controlled segments before rejection

Quick assessment

Affected
authlib joserfc
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.

joserfc 是一个 Python 库，实现了多项 JSON 对象签名与加密（JOSE）标准。在 1.7.6 版本之前，joserfc 在对紧凑格式的 JWS 进行反序列化时，会在执行现有的聚合段大小限制检查之前，先调用 bytes.split()。当攻击者控制的紧凑序列化字节被传入 deserialize_compact() 时，split 操作会在 ExceededSizeError 拒绝这些段之前，先创建头（header）、载荷（payload）和签名（signature）段的副本，导致产生与所提供令牌大小

CVSS 6.9 · Medium

Possible ATT&CK Techniques 1 AI

T1499.003 · Application Exhaustion Flood
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I. Basic Information for CVE-2026-119284

Vulnerability Information
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Vulnerability Title
joserfc: Compact JWS size guard allocates attacker-controlled segments before rejection
Source: CVE Program / CVE List V5
Vulnerability Description
joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.7.6, joserfc compact JWS deserialization calls bytes.split() before enforcing the existing aggregate segment-size limits. When attacker-controlled compact serialization bytes reach deserialize_compact(), the split creates copies of the header, payload, and signature segments before ExceededSizeError rejects them, causing an additional allocation approximately proportional to the supplied token. Requests that exhaust available process memory can therefore cause an availability failure even though signature verification fails. This issue is fixed in version 1.7.6.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
authlib joserfc < 1.7.6 -

II. Public POCs for CVE-2026-119284

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III. Intelligence Information for CVE-2026-119284

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Other References for CVE-2026-119284 (3)

IV. Related Vulnerabilities

Same product: joserfc
Same vendor: authlib
Same weakness: CWE-400