ID CVE-2021-21239
Summary PySAML2 is a pure python implementation of SAML Version 2 Standard. PySAML2 before 6.5.0 has an improper verification of cryptographic signature vulnerability. Users of pysaml2 that use the default CryptoBackendXmlSec1 backend and need to verify signed SAML documents are impacted. PySAML2 does not ensure that a signed SAML document is correctly signed. The default CryptoBackendXmlSec1 backend is using the xmlsec1 binary to verify the signature of signed SAML documents, but by default xmlsec1 accepts any type of key found within the given document. xmlsec1 needs to be configured explicitly to only use only _x509 certificates_ for the verification process of the SAML document signature. This is fixed in PySAML2 6.5.0.
References
Vulnerable Configurations
  • cpe:2.3:a:pysaml2_project:pysaml2:-:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:-:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:0.1:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:0.1:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:0.2:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:0.2:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:0.4:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:0.4:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:0.4.1:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:0.4.1:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:0.4.2:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:0.4.2:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:0.4.3:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:0.4.3:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:1.0.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:1.0.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:1.0.1:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:1.0.1:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:1.0.3:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:1.0.3:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:2.0.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:2.0.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:2.1.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:2.1.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:2.2.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:2.2.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:2.3.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:2.3.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:2.4.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:2.4.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:3.0.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:3.0.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:3.0.2:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:3.0.2:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:4.0.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:4.0.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:4.1.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:4.1.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:4.2.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:4.2.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:4.3.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:4.3.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:4.4.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:4.4.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:4.5.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:4.5.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:4.6.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:4.6.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:4.6.1:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:4.6.1:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:4.6.2:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:4.6.2:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:4.6.3:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:4.6.3:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:4.6.4:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:4.6.4:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:4.6.5:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:4.6.5:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:4.7.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:4.7.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:4.8.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:4.8.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:4.9.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:4.9.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:5.0.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:5.0.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:5.1.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:5.1.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:5.2.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:5.2.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:5.3.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:5.3.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:5.4.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:5.4.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:6.0.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:6.0.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:6.1.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:6.1.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:6.2.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:6.2.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:6.3.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:6.3.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:6.3.1:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:6.3.1:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:6.4.0:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:6.4.0:*:*:*:*:*:*:*
  • cpe:2.3:a:pysaml2_project:pysaml2:6.4.1:*:*:*:*:*:*:*
    cpe:2.3:a:pysaml2_project:pysaml2:6.4.1:*:*:*:*:*:*:*
  • cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
    cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
CVSS
Base: 4.3 (as of 10-03-2021 - 21:00)
Impact:
Exploitability:
CWE CWE-347
CAPEC
  • Padding Oracle Crypto Attack
    An adversary is able to efficiently decrypt data without knowing the decryption key if a target system leaks data on whether or not a padding error happened while decrypting the ciphertext. A target system that leaks this type of information becomes the padding oracle and an adversary is able to make use of that oracle to efficiently decrypt data without knowing the decryption key by issuing on average 128*b calls to the padding oracle (where b is the number of bytes in the ciphertext block). In addition to performing decryption, an adversary is also able to produce valid ciphertexts (i.e., perform encryption) by using the padding oracle, all without knowing the encryption key. Any cryptosystem can be vulnerable to padding oracle attacks if the encrypted messages are not authenticated to ensure their validity prior to decryption, and then the information about padding error is leaked to the adversary. This attack technique may be used, for instance, to break CAPTCHA systems or decrypt/modify state information stored in client side objects (e.g., hidden fields or cookies). This attack technique is a side-channel attack on the cryptosystem that uses a data leak from an improperly implemented decryption routine to completely subvert the cryptosystem. The one bit of information that tells the adversary whether a padding error during decryption has occurred, in whatever form it comes, is sufficient for the adversary to break the cryptosystem. That bit of information can come in a form of an explicit error message about a padding error, a returned blank page, or even the server taking longer to respond (a timing attack). This attack can be launched cross domain where an adversary is able to use cross-domain information leaks to get the bits of information from the padding oracle from a target system / service with which the victim is communicating. To do so an adversary sends a request containing ciphertext to the target system. Due to the browser's same origin policy, the adversary is not able to see the response directly, but can use cross-domain information leak techniques to still get the information needed (i.e., information on whether or not a padding error has occurred). For instance, this can be done using "img" tag plus the onerror()/onload() events. The adversary's JavaScript can make web browsers to load an image on the target site, and know if the image is loaded or not. This is 1-bit information needed for the padding oracle attack to work: if the image is loaded, then it is valid padding, otherwise it is not.
Access
VectorComplexityAuthentication
NETWORK MEDIUM NONE
Impact
ConfidentialityIntegrityAvailability
NONE PARTIAL NONE
cvss-vector via4 AV:N/AC:M/Au:N/C:N/I:P/A:N
refmap via4
confirm https://github.com/IdentityPython/pysaml2/security/advisories/GHSA-5p3x-r448-pc62
misc
Last major update 10-03-2021 - 21:00
Published 21-01-2021 - 15:15
Last modified 10-03-2021 - 21:00
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