pysec-2020-143
Vulnerability from pysec
Published
2020-12-21 17:15
Modified
2020-12-23 16:09
Details

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.

Impacted products
Name purl
tlslite-ng pkg:pypi/tlslite-ng
Aliases


To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "tlslite-ng",
        "purl": "pkg:pypi/tlslite-ng"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "c28d6d387bba59d8bd5cb3ba15edc42edf54b368"
            }
          ],
          "repo": "https://github.com/tlsfuzzer/tlslite-ng",
          "type": "GIT"
        },
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.7.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.5.0-beta1",
        "0.5.0-beta2",
        "0.5.0-beta3",
        "0.5.0-beta4",
        "0.5.0-beta5",
        "0.5.0-beta6",
        "0.5.0",
        "0.5.1",
        "0.5.2",
        "0.6.0-alpha1",
        "0.6.0-alpha2",
        "0.6.0-alpha3",
        "0.6.0-alpha4",
        "0.6.0-alpha5",
        "0.6.0-beta1",
        "0.6.0",
        "0.7.0-alpha1",
        "0.7.0-alpha2",
        "0.7.0-alpha3",
        "0.7.0-alpha4",
        "0.7.0-alpha5",
        "0.7.0-alpha6",
        "0.7.0-alpha7",
        "0.7.0-alpha8",
        "0.7.0-alpha9",
        "0.7.0-beta1",
        "0.7.0",
        "0.7.1",
        "0.7.2",
        "0.7.3",
        "0.7.4",
        "0.7.5"
      ]
    }
  ],
  "aliases": [
    "CVE-2020-26263",
    "GHSA-wvcv-832q-fjg7"
  ],
  "details": "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\u0027t 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.",
  "id": "PYSEC-2020-143",
  "modified": "2020-12-23T16:09:00Z",
  "published": "2020-12-21T17:15:00Z",
  "references": [
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/tlslite-ng/"
    },
    {
      "type": "WEB",
      "url": "https://github.com/tlsfuzzer/tlslite-ng/pull/439"
    },
    {
      "type": "WEB",
      "url": "https://github.com/tlsfuzzer/tlslite-ng/pull/438"
    },
    {
      "type": "FIX",
      "url": "https://github.com/tlsfuzzer/tlslite-ng/commit/c28d6d387bba59d8bd5cb3ba15edc42edf54b368"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/tlsfuzzer/tlslite-ng/security/advisories/GHSA-wvcv-832q-fjg7"
    },
    {
      "type": "WEB",
      "url": "https://securitypitfalls.wordpress.com/2018/08/03/constant-time-compare-in-python/"
    }
  ]
}


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