CVE-2021-3531: A flaw was found in the Red Hat Ceph Storage RGW in versions before 14.2.21

This month

MEDIUM 5.3REMOTEWATCHLISTUPGRADEDOWNGRADEMITIGATE

CVE-2021-3531 is a medium-severity flaw (CVSS 5.3) affecting ceph, ceph storage, fedora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A flaw was found in the Red Hat Ceph Storage RGW in versions before 14.2.21. When processing a GET Request for a swift URL that ends with two slashes it can cause the rgw to crash, resulting in a denial of service. The greatest threat to the system is of availability.

Why this priority

Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.2% (top 18%)
CISA exploited list	No
Weakness	CWE-20, CWE-617
Published	2021-05-18
Last modified	2026-06-17

Publisher (CNA): Red Hat, Inc. · Vendor: fedoraproject · redhat

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-05-18 12:15 UTCPublished CVE record published
2026-06-17 04:05 UTCUpdated Record last modified

redhat ceph UPGRADE

Affected: < 14.2.21

Fixed in: 14.2.21

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy ceph || rpm -q ceph || ceph --version

2. UPGRADE to 14.2.21 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade ceph

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade ceph

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

redhat ceph storage DOWNGRADE

Affected: 4.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.0

1. Check installed version

apt-cache policy ceph-storage || rpm -q ceph-storage || ceph-storage --version

2. No fixed release: DOWNGRADE to a release before 4.0 (Debian / Ubuntu)

apt-cache madison ceph-storage sudo apt install ceph-storage=<VERSION_BEFORE_4.0> sudo apt-mark hold ceph-storage

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list ceph-storage sudo dnf downgrade ceph-storage-<VERSION_BEFORE_4.0> sudo dnf versionlock add ceph-storage

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

fedoraproject fedora MITIGATE

Affected: 32 · 33 · 34

Fixed in: no fixed release known

Safe to downgrade to: a release before 32

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-3531?

ceph: upgrade to 14.2.21; ceph storage: downgrade or apply the listed mitigation; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-3531 being exploited?

CVE-2021-3531 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-3531 affect?

CVE-2021-3531 affects ceph, ceph storage, fedora. Severity is medium (CVSS 5.3). A flaw was found in the Red Hat Ceph Storage RGW in versions before 14.2.21. When processing a GET Request for a swift URL that ends with two slashes it can cause the rgw to crash, resulting in a denial of service. The greatest threat to th

How urgent is CVE-2021-3531?

Priority 49/100. Remotely exploitable, no login, no user action; On your watchlist

Software pages

Ceph vulnerabilities · Swift vulnerabilities

Related CVEs

CVE-2024-47866 HIGH 7.5 UPGRADE Ceph is a distributed object, block, and file storage platform
CVE-2022-3650 HIGH 7.8 DOWNGRADE A privilege escalation flaw was found in Ceph
CVE-2022-0670 CRITICAL 9.1 UPGRADE UPGRADE A flaw was found in Openstack manilla owning a Ceph File system "share", which enables the owner to read/write
CVE-2021-3524 MEDIUM 6.5 UPGRADE DOWNGRADE A flaw was found in the Red Hat Ceph Storage RadosGW (Ceph Object Gateway) in versions before 14.2.21
CVE-2021-20288 HIGH 7.2 UPGRADE DOWNGRADE An authentication flaw was found in ceph in versions before 14.2.20

References

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