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CVE-2026-54330— Ceph RGW SigV4 handler accepts unsigned x-amz-* headers on presigned requests, allowing privilege escalation

Quick assessment

Affected
ceph ceph
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Ceph 是一个开源的分布式存储平台，提供对象、块和文件存储功能。在 20.2.4 和 19.2.6 之前的版本中，Ceph 对象网关（RGW）的 SigV4 处理器不会拒绝那些携带了签名头集合中未包含的 头的请求，这使得任何持有预签名 URL 的用户都能附加任意的未签名 头，而 RGW 将会接受这些头。 AWS S3 要求 SigV4 请求中出现的每一个 头都必须包含在签名范围内，并会拒绝带有额外未签名头的请求；但 RGW 仅验证 中列出的头，而忽略其他额外的头，导致这些未签名的头也能生效。攻击者可以通过向预签名

CVSS 8.1 · High EPSS 0.18% · P8

Possible ATT&CK Techniques 1 AI

T1531 · Account Access Removal

Affected Version Matrix 2

VendorProduct Version RangeStatus
ceph ceph >= 19.0.0, < 19.2.6 affected
>= 20.0.0, < 20.2.4 affected
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I. Basic Information for CVE-2026-54330

Vulnerability Information
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Vulnerability Title
Ceph RGW SigV4 handler accepts unsigned x-amz-* headers on presigned requests, allowing privilege escalation
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
密码学签名的验证不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
ceph ceph >= 19.0.0, < 19.2.6 -

II. Public POCs for CVE-2026-54330

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III. Intelligence Information for CVE-2026-54330

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Patches & Fixes for CVE-2026-54330 (2)

Vendor Advisories for CVE-2026-54330 (1)

Same Patch Batch · ceph · 2026-08-27 · 4 CVEs total

CVE-2026-50152 9.1 CRITICAL Ceph Monitor subscription handler improperly authorizes config-key store reads, exposing c
CVE-2025-30156 8.9 HIGH Ceph: AES-CBC misuse in CephX and RADOSGW enables authentication bypass and credential for
CVE-2026-39944 8.8 HIGH Ceph: CephX AES Authentication error

IV. Related Vulnerabilities

Same product: ceph
Same vendor: ceph
Same weakness: CWE-347

V. Comments for CVE-2026-54330

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