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Fencer Intel
high 8.1

CVE-2026-54330 json

Ceph RGW SigV4 handler accepts unsigned x-amz-* headers on presigned requests, allowing privilege escalation

published 2mo ago modified 2mo ago also BIT-ceph-2026-54330 , EUVD-2026-67276 , GHSA-rmjq-ffrm-j6vj

cvss
8.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 30%
public exploits
0
none known

Summary

Ceph is an open-source distributed storage platform providing object, block, and file storage. In versions prior to 20.2.4 and 19.2.6, the Ceph Object Gateway (RGW) SigV4 handler does not reject requests that carry x-amz-* headers absent from the signed header set, allowing anyone holding a presigned URL to attach arbitrary unsigned x-amz-* headers that RGW will honor. AWS S3 requires every x-amz-* header on a SigV4 request to be signed and rejects requests bearing additional unsigned headers, but RGW validates only the headers listed in X-Amz-SignedHeaders and ignores any extra ones, so they take effect without being covered by the signature. By adding such headers to a presigned PUT URL, an attacker can grant themselves more capabilities than the URL's signer intended and escalate their privileges. This issue is fixed in versions 20.2.4 and 19.2.6.

Patch / fix

  • bitnami ceph 19.2.6, 20.2.4
  • linuxfoundation ceph 19.2.6, 20.2.4
  • redhat ceph 19.2.6, 20.2.4
  • ceph Debian 14 20.2.4+ds-1

debian advisories DEBIAN-CVE-2026-54330

  • ceph Ubuntu 22.04 LTS 17.2.9-0ubuntu0.22.04.4
  • ceph Ubuntu 26.04 LTS 20.2.0-0ubuntu2.1
  • ceph Ubuntu Pro 18.04 LTS 12.2.13-0ubuntu0.18.04.11+esm3
  • ceph Ubuntu Pro 20.04 LTS 15.2.17-0ubuntu0.20.04.6+esm2

ubuntu advisories UBUNTU-CVE-2026-54330

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • ceph ceph storage 8.1 2:19.2.1-423.el9cp
  • cephadm ceph storage 8.1 2:19.2.1-423.el9cp
  • librbd1 ceph storage 8.1 2:19.2.1-423.el9cp
  • librgw2 ceph storage 8.1 2:19.2.1-423.el9cp
  • rbd-nbd ceph storage 8.1 2:19.2.1-423.el9cp
  • ceph-mib ceph storage 8.1 2:19.2.1-423.el9cp
  • ceph-base ceph storage 8.1 2:19.2.1-423.el9cp
  • ceph-fuse ceph storage 8.1 2:19.2.1-423.el9cp

red hat advisories RHSA-2026:79101

  • ceph Azure Linux 3.0 18.2.2-13

azure linux advisories AZL-98340

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Is CVE-2026-54330 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-54330 updated cvss 8.2

ceph: ceph: RGW SigV4 verifier allows attachment of arbitrary unsigned x-amz-* headers leading to privilege escalation

  • Red Hat Ceph Storage 4 ceph, librbd1, librgw2, rbd-nbd, ceph-mds, ceph-mgr, +27 more Red Hat Ceph Storage 5 ceph, cephadm, librbd1, librgw2, rbd-nbd, ceph-mds, +33 more Red Hat Ceph Storage 6 ceph, cephadm, librbd1, librgw2, rbd-nbd, ceph-mib, +16 more Red Hat Ceph Storage 7 ceph, cephadm, librbd1, librgw2, rbd-nbd, ceph-mib, +17 more Red Hat Ceph Storage 9 ceph, cephadm, librbd1, librgw2, rbd-nbd, ceph-mib, +18 more
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Ceph Storage 8.1 rhceph/rhceph-8-rhel9 1791176990
    fixed: vendor fix RHSA-2026:79243
  • Red Hat Ceph Storage 8.1 Tools ceph 19.2.1-423.el9cp, cephadm 19.2.1-423.el9cp, librbd1 19.2.1-423.el9cp, librgw2 19.2.1-423.el9cp, rbd-nbd 19.2.1-423.el9cp, ceph-mib 19.2.1-423.el9cp, +17 more
    fixed: vendor fix RHSA-2026:79101
  • Red Hat Ceph Storage 8.1 rhceph/grafana-rhel9 1791176238, rhceph/keepalived-rhel9 1791175257, rhceph/oauth2-proxy-rhel9 1791176282, rhceph/snmp-notifier-rhel9 1791176336, rhceph/rhceph-haproxy-rhel9 1791176338, rhceph/rhceph-promtail-rhel9 1791176366
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
2mo ago

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 30% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
OSV 3.1 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Affected packages

ecosystem package affected fixed in
bitnami ceph
>=19.0.0, <19.2.6
>=20.0.0, <20.2.4
19.2.6
20.2.4

Affected products

  • ceph ceph

Classification

Weakness
  • CWE-347 Improper Verification of Cryptographic Signature

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of ceph/ceph published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.