CVE-2021-20288

An authentication flaw was found in ceph in versions before 14.2.20. When the monitor handles CEPHX_GET_AUTH_SESSION_KEY requests, it doesn't sanitize other_keys, allowing key reuse. An attacker who can request a global_id can exploit the ability of any user to request a global_id previously associated with another user, as ceph does not force the reuse of old keys to generate new ones. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

Published: 2021-04-15 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-20288 is rated Moderate Risk (41.2/100): CVSS High severity, with low exploitation likelihood (EPSS 0.18%). Review affected assets and schedule remediation.

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

Exploit prediction scoring system (EPSS) score for CVE-2021-20288

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 2025-11-21 1.71% 0.18% -1.53%
2 2025-11-18 0.24% 1.71% +1.47%
3 2025-03-30 — 0.24% —

Full EPSS history (15 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-20288

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.2 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
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:H)
They need powerful rights—admin, root, or similar—before this pays off.
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:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.2 5.9 [email protected]
6.5 2.0 MEDIUM
AV:N/AC:L/Au:S/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.0 6.4 [email protected]

Weakness enumeration for CVE-2021-20288

OS Trackers for CVE-2021-20288

vendor priority summary link
alpine — CVE-2021-20288: 2 source package rows (ceph, ceph16); 7 state rows across 3 repos (3.17-community, 3.18-community, edge-community); fixed 4, open 3. https://security.alpinelinux.org/vuln/CVE-2021-20288
debian not yet assigned CVE-2021-20288 not yet assigned priority: Debian including 1 source packages (ceph), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-20288
gentoo normal CVE-2021-20288: 1 GLSA(s) (202105-39), 1 atom(s) (sys-cluster/ceph); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-20288
redhat high — https://access.redhat.com/security/cve/CVE-2021-20288
suse high CVE-2021-20288 severity important: SUSE including 370 source package names (0.38.1.5.8.40:librados2-15.2.11.83+g8a15f484c2-3.20.1, 0.38.1.5.8.40:librbd1-15.2.11.83+g8a15f484c2-3.20.1, …), 702 product×package rows across 59 product lines (Container caasp/v4/hyperkube, Container ses/6/cephcsi/cephcsi, … (59 product lines)): Fixed 532, Will Not Fix 148, Known Not Affected 22. https://www.suse.com/security/cve/CVE-2021-20288/
ubuntu medium CVE-2021-20288 medium priority: Ubuntu including 1 source packages (ceph), 9 status rows across 9 suites (bionic, focal, groovy, hirsute, impish, jammy, trusty, upstream, xenial): released 6, ignored 3. https://ubuntu.com/security/CVE-2021-20288

Affected software / configurations for CVE-2021-20288

Vendor Product Version Raw CPE
linuxfoundation ceph < 14.2.21 cpe:2.3:a:linuxfoundation:ceph:*:*:*:*:*:*:*:*
redhat ceph_storage 4.0 cpe:2.3:a:redhat:ceph_storage:4.0:*:*:*:*:*:*:*
fedoraproject fedora 32 cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
fedoraproject fedora 34 cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

References for CVE-2021-20288

cvelogic Threat Intelligence