CVE-2021-20232
Description
A flaw was found in gnutls. A use after free issue in client_send_params in lib/ext/pre_shared_key.c may lead to memory corruption and denial of service.
Statement
As mentioned in the upstream advisory and GnuTLS issue 1151 (see External References) this flaw is not easily exploitable and it only happens intermittently (denial of service is not always practical). For this reason, this flaw has been rated as having a security impact of Moderate.
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 | 3.7 | 9.8 | 9.8 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | High | Low | Low |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | High | High |
| Integrity Impact | None | High | High |
| Availability Impact | Low | High | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Red Hat CVSS v3 Score Explanation
C:N because even if this flaw was exploited, the attacker could only get a hash of such data. I:N/A:L because the handshake nevertheless fails (so there is no integrity impact), and the issue happens only intermittently (so DoS is not always practical).
Acknowledgements
Red Hat would like to thank GnuTLS project for reporting this issue. Upstream acknowledges Ivan Nikolchev as the original reporter.
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