CVE-2026-39944

HIGHPre-NVD 8.88.8
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This high-severity CVE scores 8.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3% (19th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Trending — Patch released this week
8.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 8.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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 v3
8.8
EG Score
8.8HIGHmedium confidence
EG Risk
40
EG Risk 40/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed (value × EchelonGraph’s weight)
Severity88% × 45%
The EG Score, 8.8 of 10.
Exploitation0.3% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.3%
EPSS %ILE
19th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

August 27, 2026

Last Modified

September 8, 2026

Advisory Details (1)

Auto-updated Aug 27, 2026
Patch available. Sources: github.
GitHub advisoryMentions a patch (unverified)

Ceph RGW STS tokens vulnerable to CBC bit-flip privilege escalation to RGW admin · Advisory · ceph/ceph · GitHub

https://github.com/ceph/ceph/security/advisories/GHSA-j73r-qrgx-jvq2

Vendor Advisories for CVE-2026-39944(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(2)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatceph-2:19.2.1-423.el9cp2026-10-08redhat
redhatrhceph/rhceph-8-rhel9:17911769902026-10-08redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
ceph16.2.11+ds-2 ... 20.2.4+ds-1 (63 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
ceph18.2.7+ds-1 ... 20.2.4+ds-1 (20 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
ceph18.2.7+ds-1 ... 20.2.2+ds-9 (18 versions)
  • every version up to 20.2.4+ds-1: fixed in 20.2.4+ds-1
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 17× in last 7d / 56× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 1 repeat row among the latest 94 is merged into the row it repeats.

  1. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  2. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  3. 2026-10-12 16:10 UTCEG score recompute
  4. 2026-10-11 19:52 UTCEG score recompute
  5. 2026-10-11 17:05 UTCEG score recompute
  6. 2026-10-11 14:32 UTCEG score recompute
  7. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  9. 2026-10-10 13:46 UTCVendor advisory
  10. 2026-10-10 01:45 UTCEG score recompute
  11. 2026-10-10 01:45 UTCVendor advisory
  12. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  13. 2026-10-09 02:55 UTCEG score recompute
  14. 2026-10-09 02:55 UTCVendor advisory
  15. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  16. 2026-10-08 01:13 UTCEG score recompute
  17. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  18. 2026-10-07 02:53 UTCEG score recompute
  19. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  20. 2026-10-06 02:28 UTCEG score recompute
  21. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  22. 2026-10-05 02:36 UTCEG score recompute
  23. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  24. 2026-10-03 14:56 UTCEG score recompute
  25. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.3% · 19th percentile
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  1. 2026-10-02 19:48 UTCEG score recompute
  2. 2026-10-01 19:52 UTCEG score recompute
  3. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  4. 2026-09-30 19:53 UTCEG score recompute
  5. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  6. 2026-09-30 04:53 UTCEG score recompute
  7. 2026-09-29 12:12 UTCEG score recompute
  8. 2026-09-28 21:12 UTCEG score recompute
  9. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  10. 2026-09-27 18:36 UTCEG score recompute
  11. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  12. 2026-09-26 18:23 UTCEG score recompute
  13. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  14. 2026-09-26 00:26 UTCEPSS rescoreEPSS 0.3% · 18th percentile
  15. 2026-09-24 23:28 UTCEG score recompute
  16. 2026-09-23 23:27 UTCEG score recompute
  17. 2026-09-22 23:40 UTCEG score recompute
  18. 2026-09-21 23:39 UTCEG score recompute
  19. 2026-09-20 23:50 UTCEG score recompute
  20. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  21. 2026-09-19 23:37 UTCEG score recompute
  22. 2026-09-18 23:49 UTCEG score recompute
  23. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  24. 2026-09-18 00:02 UTCEG score recompute
  25. 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  26. 2026-09-16 23:22 UTCEG score recompute
  27. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  28. 2026-09-16 11:28 UTCEG score recompute
  29. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  30. 2026-09-15 11:32 UTCEG score recompute
  31. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  32. 2026-09-13 23:25 UTCEG score recompute
  33. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  34. 2026-09-12 23:38 UTCEG score recompute
  35. 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  36. 2026-09-11 23:48 UTCEG score recompute
  37. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  38. 2026-09-11 11:54 UTCEG score recompute
  39. 2026-09-11 09:37 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  40. 2026-09-10 11:52 UTCEG score recompute
  41. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  42. 2026-09-09 09:48 UTCEG score recompute
  43. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  44. 2026-09-08 03:31 UTCEG score recompute
  45. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  46. 2026-09-06 15:46 UTCEG score recompute
  47. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  48. 2026-09-05 15:59 UTCEG score recompute
  49. 2026-09-04 16:11 UTCEG score recompute
  50. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  51. 2026-09-02 16:30 UTCEG score recompute
  52. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  53. 2026-09-01 16:36 UTCEG score recompute
  54. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  55. 2026-09-01 04:39 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  56. 2026-09-01 04:39 UTCEG score recompute
  57. 2026-09-01 04:04 UTCEG score recompute
  58. 2026-08-30 20:16 UTCEG score recompute
  59. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  60. 2026-08-30 08:23 UTCEG score recompute
  61. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  62. 2026-08-29 08:33 UTCEG score recompute
  63. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  64. 2026-08-28 20:39 UTCEG score recompute
  65. 2026-08-28 19:46 UTCEG score recompute
  66. 2026-08-28 00:31 UTCEG score recompute
  67. 2026-08-27 23:23 UTCEG score recomputeFirst assessed: 8.8 HIGH
  68. 2026-08-27 23:23 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-39944?
CVE-2026-39944 is a high-severity vulnerability; its CVE record was published on August 27, 2026. 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…
When was the CVE record for CVE-2026-39944 published?
The CVE record for CVE-2026-39944 was published on August 27, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 8, 2026; the record at its source may have been updated since.
Is CVE-2026-39944 actively exploited?
CVE-2026-39944 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (19th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-39944?
CVE-2026-39944 has a CVSS base score of 8.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-39944?
A fix for CVE-2026-39944 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-39944 are linked in the Vendor Advisories panel on this page.

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