SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2020-1971

A NULL pointer dereference and a crash may occur leading to a possible denial of service attack.

MEDIUM 5.9EPSS 6.99%

Does this matter?

Lower severity and a low EPSS score (6.99%). Track it; it rarely justifies an emergency change on its own.

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).

CVSS 3.1
5.9 MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
6.99% probability · 94th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-476
Affected
openssl/openssl · debian/debian linux · fedoraproject/fedora · oracle/api gateway · oracle/business intelligence · oracle/communications cloud native core network function cloud native environment · oracle/communications diameter intelligence hub · oracle/communications session border controller · oracle/communications session router · oracle/communications subscriber-aware load balancer · oracle/communications unified session manager · oracle/enterprise communications broker · oracle/enterprise manager base platform · oracle/enterprise manager for storage management · oracle/enterprise manager ops center · oracle/enterprise session border controller · oracle/essbase · oracle/graalvm · oracle/http server · oracle/jd edwards enterpriseone tools · +24 more
Source
openssl-security@openssl.org
EPSS trend
0%5%10%26 October 2026: 6.99%26 October 202626 October 2026

EPSS 7.0% since 26 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.