CVE-2026-39944: high-severity vulnerability in ceph
Ceph: CephX AES Authentication error
Published · Updated
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8.8epss 0.3%
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 RADOS Gateway (RGW) protects STS session tokens with an AES-128-CBC handler that provides no message authentication, allowing an attacker who holds any valid STS token to tamper with it undetected and escalate to full RGW administrative access. Because the ciphertext is unauthenticated, the attacker can perform a CBC bit-flip on the acct_type, perm_type, and is_admin fields of their own token, and a forged is_admin value triggers a global administrative override that bypasses all capability checks. The attack is reachable remotely over the RGW S3 endpoint and is a self-contained modification of a token the attacker already possesses, requiring no encryption oracle and no network observation. It requires only a single valid STS token, which need not carry any elevated privileges, with STS enabled. This issue is fixed in versions 20.2.4 and 19.2.6.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Affected products
ceph · cephRelated CVEs — ceph
In the same product, most dangerous first.
CVE-2024-47866HIGHRGW DoS attack with empty HTTP header in S3 object copyEPSS 0.5%CVE-2026-54330HIGHCeph RGW SigV4 handler accepts unsigned x-amz-* headers on presigned requests, allowing privilege escalationEPSS 0.4%CVE-2026-50152CRITICALCeph Monitor subscription handler improperly authorizes config-key store reads, exposing cluster secrets to read-only usersEPSS 0.2%CVE-2024-48916HIGHCeph is vulnerable to authentication bypass through RadosGWEPSS 0.2%CVE-2025-52555MEDIUMCephFS Permission Escalation Vulnerability in Ceph Fuse mounted FSEPSS 0.2%CVE-2025-30156HIGHCeph: AES-CBC misuse in CephX and RADOSGW enables authentication bypass and credential forgeryEPSS 0.1%