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.
Conclusion & alert: CVE-2021-3521 is rated Low Risk (26.7/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.30%). Mandatory action: Monitor for updates and reassess as exploit intelligence or EPSS changes.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-06-15 | 0.03% | 0.30% | +0.28% |
| 2 | 2025-03-17 | 0.05% | 0.03% | -0.02% |
| 3 | 2023-09-24 | — | 0.05% | — |
Full EPSS history (8 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 4.7 | 3.1 | MEDIUM |
|
1.0 | 3.6 | [email protected] |
| vendor | priority | summary | link |
|---|---|---|---|
alpine
|
medium | CVE-2021-3521: 1 source package rows (rpm); 12 state rows across 7 repos (3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 7, open 5. | https://security.alpinelinux.org/vuln/CVE-2021-3521 |
debian
|
not yet assigned | CVE-2021-3521 not yet assigned priority: Debian including 1 source packages (rpm), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 4, open 1. | https://security-tracker.debian.org/tracker/CVE-2021-3521 |
gentoo
|
high | CVE-2021-3521: 1 GLSA(s) (202210-22), 1 atom(s) (app-arch/rpm); latest impact high. | https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-3521 |
redhat
|
medium | — | https://access.redhat.com/security/cve/CVE-2021-3521 |
suse
|
medium | CVE-2021-3521 severity moderate: SUSE including 65 source package names (13.2-5.15.25:rpm-ndb-4.14.3-150400.59.16.1, 13.2-6.8.26:rpm-ndb-4.14.3-150400.59.16.1, …), 667 product×package rows across 303 product lines (Container bci/bci-minimal, Container bci/bci-sle15-kernel-module-devel, … (303 product lines)): Fixed 613, Known Not Affected 54. | https://www.suse.com/security/cve/CVE-2021-3521/ |
ubuntu
|
negligible | CVE-2021-3521 negligible priority: Ubuntu including 1 source packages (rpm), 15 status rows across 15 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): needs-triage 8, ignored 7. | https://ubuntu.com/security/CVE-2021-3521 |
| URL | Tags |
|---|---|
| https://access.redhat.com/security/cve/CVE-2021-3521 | Third Party Advisory |
| https://bugzilla.redhat.com/show_bug.cgi?id=1941098 | Issue Tracking Patch Third Party Advisory |
| https://github.com/rpm-software-management/rpm/commit/bd36c5dc9fb6d90c46fbfed8c2d67516fc571ec8 | Patch Third Party Advisory |
| https://github.com/rpm-software-management/rpm/pull/1795/ | Patch Third Party Advisory |
| https://security.gentoo.org/glsa/202210-22 | Third Party Advisory |