CVE-2021-3521
Description
There is a flaw in RPM's signature functionality. OpenPGP subkeys are associated with a primary key via a "binding signature."[1] RPM does not check the binding signature of subkeys prior to importing them. If an attacker is able to add or socially engineer another party to add a malicious subkey to a legitimate public key, RPM could wrongly trust a malicious signature. The greatest impact of this flaw is to data integrity.
Statement
To exploit this flaw, an attacker must either compromise an RPM repository or convince an administrator to install an untrusted RPM or public key. It is strongly recommended to only use RPMs and public keys from trusted sources.
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 | 4.4 | 4.7 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | High | High | N/A |
| Privileges Required | Low | None | N/A |
| User Interaction | Required | Required | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N
NVD: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N
Understanding the Weakness (CWE)
Access Control,Integrity,Confidentiality
Technical Impact: Gain Privileges or Assume Identity; Modify Application Data; Execute Unauthorized Code or Commands
An attacker could gain access to sensitive data and possibly execute unauthorized code.
Acknowledgements
Red Hat would like to thank Demi M. Obenour for reporting this issue.
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