CVE-2021-3505

Exp

A flaw was found in libtpms in versions before 0.8.0. The TPM 2 implementation returns 2048 bit keys with ~1984 bit strength due to a bug in the TCG specification. The bug is in the key creation algorithm in RsaAdjustPrimeCandidate(), which is called before the prime number check. The highest threat from this vulnerability is to data confidentiality.

Published: 2021-04-19 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-3505 is rated Exploit Available (50/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.40%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-3505

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-3505

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 0.06% 0.40% +0.35%
2 2023-07-12 0.04% 0.06% +0.01%
3 2023-03-07 — 0.04% —

Full EPSS history (8 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-3505

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.5 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 1.8 3.6 [email protected]
2.1 2.0 LOW
AV:L/AC:L/Au:N/C:P/I:N/A:N Click to expand
Access vector (AV:L)
Requires local access to the target system.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 3.9 2.9 [email protected]

Weakness enumeration for CVE-2021-3505

OS Trackers for CVE-2021-3505

vendor priority summary link
debian not yet assigned CVE-2021-3505 not yet assigned priority: Debian including 1 source packages (libtpms), 4 status rows across 4 suites (bookworm, forky, sid, trixie): resolved 4. https://security-tracker.debian.org/tracker/CVE-2021-3505
redhat low — https://access.redhat.com/security/cve/CVE-2021-3505
suse medium CVE-2021-3505 severity moderate: SUSE including 13 source package names (libtpms-devel-0.8.2-1.1, libtpms-devel-0.8.2-3.3.1, …), 18 product×package rows across 14 product lines (SUSE Linux Enterprise Micro 5.1, SUSE Linux Enterprise Micro 5.2, … (14 product lines)): Fixed 18. https://www.suse.com/security/cve/CVE-2021-3505/
ubuntu low CVE-2021-3505 low priority: Ubuntu including 1 source packages (libtpms), 6 status rows across 6 suites (bionic, focal, groovy, trusty, upstream, xenial): DNE 4, not-affected 1, released 1. https://ubuntu.com/security/CVE-2021-3505

Affected software / configurations for CVE-2021-3505

Vendor Product Version Raw CPE
libtpms_project libtpms < 0.8.0 cpe:2.3:a:libtpms_project:libtpms:*:*:*:*:*:*:*:*
redhat enterprise_linux 8.0 cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:advanced_virtualization:*:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*

References for CVE-2021-3505

cvelogic Threat Intelligence