CVE-2020-26263 RSA vulnerability in tslite-ng

2020-12-2116:55:18

CWE-326

GitHub_M

www.cve.org

7.5 High

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

HIGH

Availability Impact

NONE

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

0.003 Low

EPSS

Percentile

69.6%

JSON

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.

CNA Affected

[
  {
    "product": "tlslite-ng",
    "vendor": "tlsfuzzer",
    "versions": [
      {
        "status": "affected",
        "version": "< 0.7.6"
      },
      {
        "status": "affected",
        "version": ">= 0.8.0-alpha1, < 0.8.0-alpha39"
      }
    ]
  }
]