CVE-2021-3449
Description
A flaw was found in openssl. A server crash and denial of service attack could occur if a client sends a TLSv1.2 renegotiation ClientHello and omits the signature_algorithms extension but includes a signature_algorithms_cert extension. The highest threat from this vulnerability is to system availability.
Statement
This flaw only affects OpenSSL 1.1.1, older versions are not affected.
Mitigation
This flaw can be mitigated by disabling TLS renegotiation on servers compiled with OpenSSL. It is enabled by default, but can be disabled for servers which do not require it and can be used to mitigate this flaw. Versions of httpd package shipped with Red Hat Enterprise Linux 8 have TLS renegotiation disabled by default.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.9 | 5.9 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | High | High | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Acknowledgements
Red Hat would like to thank the OpenSSL project for reporting this issue. Upstream acknowledges Nokia as the original reporter.
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