TI-2026-39225 Aliases CVE-2026-54330

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

LOW 37CWE-347Published 2026-08-27 · Updated 2026-09-01

Key facts

Attack vector: Network
Privileges required: Low
User interaction: None
Attack complexity: Low
Impact type: Security bypass
Confidentiality · integrity · availability: High · High · None
Fix status: Partial Red Hat: 2 fixed, 5 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-347.

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00367 30th percentileScored 2026-11-07

Fix Partial ceph (ceph): 19.2.6, 20.2.4Red Hat: 2 advisoriesRed Hat: 2 fixed, 5 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
ceph	ceph	19.0.0 to before 19.2.6; 20.0.0 to before 20.2.4	19.2.6, 20.2.4	Patch available	CNA

ceph Vendorceph Affected 19.0.0 to before 19.2.6; 20.0.0 to before 20.2.4 Fixed in 19.2.6, 20.2.4 Patch available CNA

Remediation

Fix · CNA ceph (ceph) Fixed in 19.2.6, 20.2.4

Red Hat 2 advisories

RHSA-2026:79243 Released 2026-10-08 · Red Hat rating Important
Red Hat Ceph Storage
- Red Hat Ceph Storage 8.1 registry.redhat.io/rhceph/grafana-rhel9, registry.redhat.io/rhceph/rhceph-8-rhel9
RHSA-2026:79101 Released 2026-10-08 · Red Hat rating Important
Red Hat Ceph Storage 8.1 security and bug fix updates
- Red Hat Ceph Storage 8.1 Tools ceph-2:19.2.1-423.el9cp, ceph-base-2:19.2.1-423.el9cp, ceph-common-2:19.2.1-423.el9cp +25

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

Product	Status	Plan or fix
Red Hat Ceph Storage 4	Affected	No fix yet: Fix deferred
Red Hat Ceph Storage 5	Affected	No fix yet: Fix deferred
Red Hat Ceph Storage 6	Affected	No fix yet: Fix deferred
Red Hat Ceph Storage 7	Affected	No fix yet: Fix deferred
Red Hat Ceph Storage 9	Affected	No fix yet: Fix deferred
Red Hat Ceph Storage 8.1	Fixed	RHSA-2026:79243
Red Hat Ceph Storage 8.1 Tools	Fixed	RHSA-2026:79101

Not affected: 1 product

Red Hat Ceph Storage 8.1

Timeline

2026-10-02 Threatist record created from CVE-2026-54330
2026-10-09 Fix available: RHSA-2026:79101 · Red Hat
2026-10-09 Fix available: RHSA-2026:79243 · Red Hat
2026-10-09 Fix available: Red Hat Ceph Storage 8.1, Red Hat Ceph Storage 8.1 Tools · Red Hat

References

Other 3

TI-2024-32613 Ceph is vulnerable to authentication bypass through RadosGW CVSS 3.1HIGH 8.1
TI-2024-32120 RGW DoS attack with empty HTTP header in S3 object copy CVSS 3.1HIGH 7.5
TI-2026-36920 Improper authorization in ceph CVSS 3.1CRITICAL 9.1
TI-2020-01660 Hard-coded credentials in ceph-ansible CVSS 3.1HIGH 8.8
TI-2018-07675 Improper authorization in Red Hat ceph CVSS 3.0HIGH 8.1
TI-2026-28807 Ceph: CephX AES Authentication error CVSS 3.1HIGH 8.8

See all 17 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences