CVE-2023-3817 Excessive time spent checking DH q parameter value

2023-07-3115:34:13

openssl

www.cve.org

dh parameters

denial of service

openssl functions

untrusted source

fips

6.2 Medium

AI Score

Confidence

High

0.003 Low

EPSS

Percentile

65.5%

JSON

Issue summary: Checking excessively long DH keys or parameters may be very slow.

Impact summary: Applications that use the functions DH_check(), DH_check_ex()
or EVP_PKEY_param_check() to check a DH key or DH parameters may experience long
delays. Where the key or parameters that are being checked have been obtained
from an untrusted source this may lead to a Denial of Service.

The function DH_check() performs various checks on DH parameters. After fixing
CVE-2023-3446 it was discovered that a large q parameter value can also trigger
an overly long computation during some of these checks. A correct q value,
if present, cannot be larger than the modulus p parameter, thus it is
unnecessary to perform these checks if q is larger than p.

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

The function DH_check() is itself called by a number of other OpenSSL functions.
An application calling any of those other functions may similarly be affected.
The other functions affected by this are DH_check_ex() and
EVP_PKEY_param_check().

Also vulnerable are the OpenSSL dhparam and pkeyparam command line applications
when using the “-check” option.

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

The OpenSSL 3.0 and 3.1 FIPS providers are not affected by this issue.

CNA Affected

[
  {
    "defaultStatus": "unaffected",
    "product": "OpenSSL",
    "vendor": "OpenSSL",
    "versions": [
      {
        "lessThan": "3.1.2",
        "status": "affected",
        "version": "3.1.0",
        "versionType": "semver"
      },
      {
        "lessThan": "3.0.10",
        "status": "affected",
        "version": "3.0.0",
        "versionType": "semver"
      },
      {
        "lessThan": "1.1.1v",
        "status": "affected",
        "version": "1.1.1",
        "versionType": "custom"
      },
      {
        "lessThan": "1.0.2zi",
        "status": "affected",
        "version": "1.0.2",
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      }
    ]
  }
]