Evidence used
- No CISA KEV confirmation is currently recorded.
- EPSS is 0.29% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-39944High confidence
Ceph: CephX AES Authentication error
ceph · ceph
Official source article: GitHub GHSA-J73R-QRGX-JVQ2 ↗. Check the applicable product and release in the original source.
8.8HighCVSS 3.1
Patch only the product branches with a verified fix
Fix availability varies by productHigh technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 197 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:High, unchanged from published severity.unchanged
Compensating controls
- Apply the linked authoritative mitigation while planning the permanent fix.
- Restrict the affected network interface to trusted sources where business-safe.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs ceph ceph and falls inside the recorded affected range.
- Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Remediation availability differs by product scope
Verified remediation exists for at least one product or source, but 197 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
- Red Hat Product Security: 195 affected or under-investigation product states without a fixed product state in the same current advisory
- Debian Security Tracker: 2 affected package states with no published fix
Distribution package intelligence
5 package statesRelease-specific package status
Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.
Package result overrides the generic status
BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 2 affected package states shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.
Repository candidate not checked
A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.
| Distribution release | Source package | Vendor state | Fixed version | Evidence |
|---|---|---|---|---|
| Debian trixietrixie · source | ceph | Affected, no fix publishedDebian currently tracks this release as open. | Not published in this feed | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian bookwormbookworm · source | ceph | Affected, no fix publishedDebian currently tracks this release as open. | Not published in this feed | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian forkyforky · source | ceph | Vendor fix publishedDebian records a fixed source-package version for this release. | 20.2.4+ds-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian sidsid · source | ceph | Vendor fix publishedDebian records a fixed source-package version for this release. | 20.2.4+ds-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | ceph | Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
Direct vendor intelligence
1 currentAuthoritative vendor CSAF and VEX advisories
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
CVE-2026-39944 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityceph: ceph: RGW STS session tokens vulnerable to CBC bit-flip attack enabling admin privilege escalation
The vendor explicitly identifies these products as affected by this CVE.
- ceph-base as a component of Red Hat Ceph Storage 4
- ceph-common as a component of Red Hat Ceph Storage 4
- ceph-fuse as a component of Red Hat Ceph Storage 4
- ceph-grafana-dashboards as a component of Red Hat Ceph Storage 4
- ceph-mds as a component of Red Hat Ceph Storage 4
- ceph-mgr as a component of Red Hat Ceph Storage 4
- ceph-mgr-dashboard as a component of Red Hat Ceph Storage 4
- ceph-mgr-diskprediction-local as a component of Red Hat Ceph Storage 4
- ceph-mgr-k8sevents as a component of Red Hat Ceph Storage 4
- ceph-mgr-rook as a component of Red Hat Ceph Storage 4
- ceph-mon as a component of Red Hat Ceph Storage 4
- ceph-osd as a component of Red Hat Ceph Storage 4
- Summary
- A flaw was found in Ceph RGW's STS (Security Token Service) session token implementation. The STS tokens use the same unauthenticated AES-128-CBC encryption as CephX, which lacks message authentication and uses a hardcoded initialization vector. Because there is no integrity protection on the tokens, an attacker who holds any valid unprivileged STS token can perform a CBC bit-flip attack to modify the token contents and escalate to full RGW admin privileges. This requires only that STS is enabled (rgw_s3_auth_use_sts = true) and that the attacker has a single valid STS token. Successful exploitation grants complete control over the RGW service, including reading, writing, and deleting all objects and buckets.
- Remediation
- Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 197 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
Fix availability varies by product01
What, why and how
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.
What
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.
Why
The product uses a broken or risky cryptographic algorithm or protocol.
How
An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may gain additional privileges.
What
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.
Why
The product uses a broken or risky cryptographic algorithm or protocol.
How
An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may gain additional privileges.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- a network path → Use of a Broken or Risky Cryptographic Algorithm → gain additional privileges
- Attack surface
- Network
- Privileges required
- Low: a basic authenticated account is required
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Unchanged: impact remains within the vulnerable component's security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-327 ↗
CWE-327: Use of a Broken or Risky Cryptographic Algorithm. The product uses a broken or risky cryptographic algorithm or protocol.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.- Post-exploitation / living off the land
- Stolen credentials, tokens and legitimate administration functions may provide continued access without deploying a large custom toolset.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Fix availability varies by product
- Affected
- ceph-base as a component of Red Hat Ceph Storage 4
- ceph-common as a component of Red Hat Ceph Storage 4
- ceph-fuse as a component of Red Hat Ceph Storage 4
- ceph-grafana-dashboards as a component of Red Hat Ceph Storage 4
- ceph-mds as a component of Red Hat Ceph Storage 4
- ceph-mgr as a component of Red Hat Ceph Storage 4
- ceph-mgr-dashboard as a component of Red Hat Ceph Storage 4
- ceph-mgr-diskprediction-local as a component of Red Hat Ceph Storage 4
- ceph-mgr-k8sevents as a component of Red Hat Ceph Storage 4
- ceph-mgr-rook as a component of Red Hat Ceph Storage 4
- ceph-mon as a component of Red Hat Ceph Storage 4
- ceph-osd as a component of Red Hat Ceph Storage 4
- ceph-radosgw as a component of Red Hat Ceph Storage 4
- ceph-selinux as a component of Red Hat Ceph Storage 4
- ceph-test as a component of Red Hat Ceph Storage 4
- ceph.src as a component of Red Hat Ceph Storage 4
- libcephfs-devel as a component of Red Hat Ceph Storage 4
- libcephfs2 as a component of Red Hat Ceph Storage 4
- librados-devel as a component of Red Hat Ceph Storage 4
- librados2 as a component of Red Hat Ceph Storage 4
- libradospp-devel as a component of Red Hat Ceph Storage 4
- libradosstriper1 as a component of Red Hat Ceph Storage 4
- librbd-devel as a component of Red Hat Ceph Storage 4
- librbd1 as a component of Red Hat Ceph Storage 4
- librgw-devel as a component of Red Hat Ceph Storage 4
- librgw2 as a component of Red Hat Ceph Storage 4
- python-ceph-argparse as a component of Red Hat Ceph Storage 4
- python-cephfs as a component of Red Hat Ceph Storage 4
- python-rados as a component of Red Hat Ceph Storage 4
- python-rbd as a component of Red Hat Ceph Storage 4
- and 165 more
- Action
- Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
- Workaround
- Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
04
Evidence and provenance
Published 27 Aug 2026 · Last source change 1 Sept 2026, 03:56 UTC · CWE-327 · Use of a Broken or Risky Cryptographic Algorithm
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-28
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-67315
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD awaiting enrichment
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
- Affected versionsThe structured affected or fixed version information changed.CNA ↗
- Before
- >= 19.0.0, < 19.2.6; >= 20.0.0, < 20.2.4 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- After
- ceph: >= 19.0.0, < 19.2.6, >= 20.0.0, < 20.2.4 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- ENISA EUVD mappingEUVD-2026-67315 was added to the official ENISA EUVD mapping for this CVE.ENISA EUVD ↗
- Before
- not recorded
- After
- {"euvdId":"EUVD-2026-67315"}
- Catalogue recordCVE added to the BlackTree catalogue.CNA ↗
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.