An OpenSSL TLS server may crash if sent a maliciously crafted renegotiation ClientHello message from a client. If a TLSv1.2 renegotiation ClientHello omits the signature_algorithms extension (where it was present in the initial ClientHello), but includes a signature_algorithms_cert extension then a NULL pointer dereference will result, leading to a crash and a denial of service attack. A server is only vulnerable if it has TLSv1.2 and renegotiation enabled (which is the default configuration). OpenSSL TLS clients are not impacted by this issue. All OpenSSL 1.1.1 versions are affected by this issue. Users of these versions should upgrade to OpenSSL 1.1.1k. OpenSSL 1.0.2 is not impacted by this issue. Fixed in OpenSSL 1.1.1k (Affected 1.1.1-1.1.1j).
Published 2021-03-25 15:15:13
Updated 2022-08-29 20:27:13
View at NVD,   CVE.org
Vulnerability category: Memory CorruptionDenial of service

Exploit prediction scoring system (EPSS) score for CVE-2021-3449

Probability of exploitation activity in the next 30 days: 0.33%

Percentile, the proportion of vulnerabilities that are scored at or less: ~ 68 % EPSS Score History EPSS FAQ

CVSS scores for CVE-2021-3449

Base Score Base Severity CVSS Vector Exploitability Score Impact Score Score Source
4.3
MEDIUM AV:N/AC:M/Au:N/C:N/I:N/A:P
8.6
2.9
NIST
5.9
MEDIUM CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
2.2
3.6
NIST

CWE ids for CVE-2021-3449

  • A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit.
    Assigned by: nvd@nist.gov (Primary)

References for CVE-2021-3449

Products affected by CVE-2021-3449

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