CVE-2021-3521: Medium severity rpm rpm vulnerability
RPM does not require subkeys to have a valid binding signature. This could potentially result in a signature being wrongly trusted in the following (rather contrived) scenario: A malicious subkey (to which an attacker has the secret key) is added to a legitimate public key, via a process that rejects main keys but not subkeys and does not itself check binding signatures. The main key is exported and then imported into RPM.
Other sources
There is a flaw in RPM's signature functionality. OpenPGP subkeys are associated with a primary key via a "binding signature." 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. 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.
— MITRE
Affected Software
Remediation
Patch Available
Patch Available
Event History
Frequently Asked Questions
What is CVE-2021-3521?
CVE-2021-3521 is a vulnerability in RPM's signature functionality that allows an attacker to add a malicious subkey.
What is the severity of CVE-2021-3521?
CVE-2021-3521 has a severity rating of 4.7, which is considered medium.
How does CVE-2021-3521 work?
CVE-2021-3521 works by bypassing the check for the binding signature of OpenPGP subkeys, allowing the import of malicious subkeys.
What software is affected by CVE-2021-3521?
RPM version up to and excluding 4.17.1 is affected by CVE-2021-3521.
Is there a fix for CVE-2021-3521?
Yes, a fix for CVE-2021-3521 is available. Please refer to the provided references for more information.