CVE-2023-6237 Excessive time spent checking invalid RSA public keys

2024-04-2506:27:26

openssl

github.com

rsa public key

denial of service

openssl fips

AI Score

7.1

Confidence

High

SSVC

Exploitation

none

Automatable

Technical Impact

partial

JSON

Issue summary: Checking excessively long invalid RSA public keys may take
a long time.

Impact summary: Applications that use the function EVP_PKEY_public_check()
to check RSA public keys may experience long delays. Where the key that
is being checked has been obtained from an untrusted source this may lead
to a Denial of Service.

When function EVP_PKEY_public_check() is called on RSA public keys,
a computation is done to confirm that the RSA modulus, n, is composite.
For valid RSA keys, n is a product of two or more large primes and this
computation completes quickly. However, if n is an overly large prime,
then this computation would take a long time.

An application that calls EVP_PKEY_public_check() and supplies an RSA key
obtained from an untrusted source could be vulnerable to a Denial of Service
attack.

The function EVP_PKEY_public_check() is not called from other OpenSSL
functions however it is called from the OpenSSL pkey command line
application. For that reason that application is also vulnerable if used
with the ‘-pubin’ and ‘-check’ options on untrusted data.

The OpenSSL SSL/TLS implementation is not affected by this issue.

The OpenSSL 3.0 and 3.1 FIPS providers are affected by this issue.

CNA Affected

[
  {
    "vendor": "OpenSSL",
    "product": "OpenSSL",
    "versions": [
      {
        "status": "affected",
        "version": "3.0.0",
        "lessThan": "3.0.13",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "3.1.0",
        "lessThan": "3.1.5",
        "versionType": "semver"
      },
      {
        "status": "affected",
        "version": "3.2.0",
        "lessThan": "3.2.1",
        "versionType": "semver"
      }
    ],
    "defaultStatus": "unaffected"
  }
]