Inadequate Encryption Strength Affecting tlslite-ng package, versions *


Severity

Recommended
low

Based on Debian security rating.

Threat Intelligence

EPSS
0.6% (79th percentile)

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  • Snyk IDSNYK-DEBIAN10-TLSLITENG-1053410
  • published22 Dec 2020
  • disclosed21 Dec 2020

Introduced: 21 Dec 2020

CVE-2020-26263  (opens in a new tab)
CWE-326  (opens in a new tab)

How to fix?

There is no fixed version for Debian:10 tlslite-ng.

NVD Description

Note: Versions mentioned in the description apply only to the upstream tlslite-ng package and not the tlslite-ng package as distributed by Debian. See How to fix? for Debian:10 relevant fixed versions and status.

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.

CVSS Scores

version 3.1