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CVE-2020-26263— RSA vulnerability in tslite-ng

Quick assessment

Affected
tlsfuzzer tlslite-ng
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Lennyniu Tlslite-ng是Lennyniu个人开发者的一个基于Python用于提供SSLv3.0, TLS 1.0, TLS 1.1 and TLS 1.2的代码库。 tlslite-ng 0.7.6和0.8.0-alpha39之前存在加密问题漏洞，该漏洞源于在RSA PKCS#1 v1.5解密中执行解密和填充检查的代码依赖于数据。具体来说，代码有多种方式可以泄露关于解密密文的信息。只要明文开头不是0x00, 0x02，它就会中止。所有启用RSA密钥交换的TLS服务器以及直接使用RSA解密A

CVSS 7.5 · High EPSS 1.52% · P74

Possible ATT&CK Techniques 1 AI

T1557 · Adversary-in-the-Middle
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I. Basic Information for CVE-2020-26263

Vulnerability Information
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Vulnerability Title
RSA vulnerability in tslite-ng
Source: CVE Program / CVE List V5
Vulnerability Description
tlslite-ng is an open source python library that implements SSL and TLS cryptographic protocols. In tlslite-ng before versions 0.7.6 and 0.8.0-alpha39, the code that performs decryption and padding check in RSA PKCS#1 v1.5 decryption is data dependant. In particular, the code has multiple ways in which it leaks information about the decrypted ciphertext. It aborts as soon as the plaintext doesn't start with 0x00, 0x02. All TLS servers that enable RSA key exchange as well as applications that use the RSA decryption API directly are vulnerable. This is patched in versions 0.7.6 and 0.8.0-alpha39. Note: the patches depend on Python processing the individual bytes in side-channel free manner, this is known to not the case (see reference). As such, users that require side-channel resistance are recommended to use different TLS implementations, as stated in the security policy of tlslite-ng.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
不充分的加密强度
Source: CVE Program / CVE List V5
Vulnerability Title
Lennyniu Tlslite-ng 加密问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Lennyniu Tlslite-ng是Lennyniu个人开发者的一个基于Python用于提供SSLv3.0, TLS 1.0, TLS 1.1 and TLS 1.2的代码库。 tlslite-ng 0.7.6和0.8.0-alpha39之前存在加密问题漏洞，该漏洞源于在RSA PKCS#1 v1.5解密中执行解密和填充检查的代码依赖于数据。具体来说，代码有多种方式可以泄露关于解密密文的信息。只要明文开头不是0x00, 0x02，它就会中止。所有启用RSA密钥交换的TLS服务器以及直接使用RSA解密A
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
tlsfuzzer tlslite-ng < 0.7.6 -

II. Public POCs for CVE-2020-26263

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 9502 chars
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III. Intelligence Information for CVE-2020-26263

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Patches & Fixes for CVE-2020-26263 (2)

Vendor Advisories for CVE-2020-26263 (1)

Other References for CVE-2020-26263 (2)

IV. Related Vulnerabilities

Same vendor: tlsfuzzer
Same weakness: CWE-326

V. Comments for CVE-2020-26263

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