CVE-2020-26263 - Inadequate Encryption Strength

Severity

75%

Complexity

39%

Confidentiality

60%

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 3.1 Base Score 7.5. CVSS Attack Vector: network. CVSS Attack Complexity: low. CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).

CVSS 2.0 Base Score 5. CVSS Attack Vector: network. CVSS Attack Complexity: low. CVSS Vector: (AV:N/AC:L/Au:N/C:P/I:N/A:N).

Overview

Type

tlslite-ng Project tlslite-ng 0.8.0 Alpha

First reported 4 years ago

2020-12-21 17:15:00

Last updated 4 years ago

2020-12-23 16:09:00

Affected Software

tlslite-ng Project tlslite-ng 0.8.0 Alpha 1

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 10

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 11

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 12

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 13

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 14

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 15

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 16

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 17

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 18

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 19

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 2

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 20

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 21

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 22

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 23

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 24

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 25

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 26

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 27

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 3

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 4

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 5

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 6

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 7

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 8

0.8.0

tlslite-ng Project tlslite-ng 0.8.0 Alpha 9

0.8.0

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