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What is CVE-2020-1971?A medium-severity flaw in OpenSSL, explained.

Medium severity46 affected products
The short answer

CVE-2020-1971 is a medium-severity flaw (CVSS 5.9) in OpenSSL, published on 8 December 2020. It is not on the list of flaws known to be exploited today. The latest forecast puts its chance of use in the next 30 days at 7.1%. If you run an affected version, plan in the vendor’s fix.

Check if it affects you →How to fix it

Published 8 December 2020. Record last updated 21 June 2024. We keep this page's data up to date.

What it does

What is CVE-2020-1971? In plain terms.

It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can take it offline.

The official description

The X.509 GeneralName type is a generic type for representing different types of names. One of those name types is known as EDIPartyName. OpenSSL provides a function GENERAL_NAME_cmp which compares different instances of a GENERAL_NAME to see if they are equal or not. This function behaves incorrectly when both GENERAL_NAMEs contain an EDIPARTYNAME. A NULL pointer dereference and a crash may occur leading to a possible denial of service attack. OpenSSL itself uses the GENERAL_NAME_cmp function for two purposes: 1) Comparing CRL distribution point names between an available CRL and a CRL distribution point embedded in an X509 certificate 2) When verifying that a timestamp response token signer matches the timestamp authority name (exposed via the API functions TS_RESP_verify_response and TS_RESP_verify_token) If an attacker can control both items being compared then that attacker could trigger a crash. For example if the attacker can trick a client or server into checking a malicious certificate against a malicious CRL then this may occur. Note that some applications automatically download CRLs based on a URL embedded in a certificate. This checking happens prior to the signatures on the certificate and CRL being verified. OpenSSL's s_server, s_client and verify tools have support for the "-crl_download" option which implements automatic CRL downloading and this attack has been demonstrated to work against those tools. Note that an unrelated bug means that affected versions of OpenSSL cannot parse or construct correct encodings of EDIPARTYNAME. However it is possible to construct a malformed EDIPARTYNAME that OpenSSL's parser will accept and hence trigger this attack. All OpenSSL 1.1.1 and 1.0.2 versions are affected by this issue. Other OpenSSL releases are out of support and have not been checked. Fixed in OpenSSL 1.1.1i (Affected 1.1.1-1.1.1h). Fixed in OpenSSL 1.0.2x (Affected 1.0.2-1.0.2w).

What kind of flaw is it?

  • CWE-476NULL Pointer Dereference
CVSS 3.1 scoreMedium · 5.9

How an attack on it works

Read straight from its severity rating, translated out of the shorthand.

  • Where an attacker can beAnywhere on the internet
  • How hard it is to pull offHard: conditions must line up
  • Login needed firstNo login needed
  • Does someone have to clickNo, nobody has to do anything
  • What an attacker getsCan take it offline

Severity vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation

Is CVE-2020-1971 being exploited? Not that we know of.

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 7.1%. That can change at any time, which is why we keep watching.

Known to be exploitedNoNot on the list of exploited flaws today
Chance of use in the next 30 days7.1%Its EPSS score, from the latest forecast

Timeline

  1. Published
  2. Record last updated
How Precursor Intelligence ranks it
47out of 100Medium

CVE-2020-1971 scores 47. Action: Plan remediation.

We keep the score of every published flaw up to date as the evidence changes. Four things go into the score, and evidence that criminals are actually using it counts most. In order:

  • Evidence it is being exploitedBiggest factor
  • How severe it isStrong factor
  • How widely exposed it isSmaller factor
  • Threat activity around itSmaller factor

85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score.

When CVE-2020-1971 matches software you track, it lands in your list with its score and the reasons behind it.

See your own ranked list →
Affected products

Who is affected by CVE-2020-1971? 46 products.

The published record lists 46 products from 8 vendors. Versions are shown as published: "1.0.2 to before 1.0.2x" means from 1.0.2 up to, but not including, 1.0.2x. If you run one of these, check your version, then go to the fix below.

Remediation

How do I fix CVE-2020-1971? Four steps.

  1. Check whether you run itCompare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list.
  2. Apply the vendor’s fixInstall the update named in the vendor’s advisory. We’ve put the advisories and patch notes first in the list.
  3. If you can’t patch todayFollow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
  4. Keep an eye on itTrack the product and we tell you as soon as we spot this flaw on the list of exploited flaws, or a jump in its exploit likelihood.

References

26 links
Precursor Intelligence

Does CVE-2020-1971 affect you? We'll keep checking.

Looking flaws up one at a time doesn't scale. Tell us what you run once, and we tell you which flaws matter to you, in what order, and keep watching for new ones.

  1. Tell us what you runPick your software from a list, or let us work it out from your website.
  2. We match it to every flawOver 400,000 published flaws, checked against your list.
  3. Ranked by real-world riskA 0 to 100 score, led by evidence criminals are using it.
  4. Told as soon as we knowAn alert by email, in the app or by webhook to your own tools.
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Common questions, answered plainly.

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CVE-2020-1971 is a medium-severity flaw in OpenSSL, published on 8 December 2020. It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can take it offline.

It scores 5.9 out of 10 on the CVSS severity scale, which is medium. Our risk score for CVE-2020-1971 is 47 out of 100, which is Medium. Its action is "Plan remediation". No sign of exploitation and a low forecast. Patch it in your normal update cycle.

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 7.1%. That can change at any time, which is why we keep watching.

For OpenSSL: 1.0.2 to before 1.0.2x, 1.1.1 to before 1.1.1i. The record lists 46 products in all, each with its versions, under "Who is affected" on this page.

Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet.

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