An access control bypass flaw was identified in Samba's vfs_ceph_rgw module in it's openat() function. An authenticated user can bypass access controls to read or overwrite restricted files on shares configured with the experimental vfs_ceph_rgw module. When a client requests an existing file using mismatched character casing, the module fails to perform a case-insensitive lookup correctly, causing the server to treat the operation as creating a new file. As a result, the server skips standard permission checks on the existing file, allowing the attacker to access or overwrite sensitive data owned by other users.
CVE-2026-109411
HIGHPre-NVD 8.18.1Trending — 5 sources updated this week
EchelonGraph scoreHIGH confidence
“—” beside the score: it is equal to the CVSS score beside it.
Score 8.1 from GitHub Security Advisory (severity: HIGH) published 2026-10-28. A secondary CVSS source baseline 8.1; sources differ by 0.0.
Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Also known asEUVD-2026-112398 (ENISA EUVD) · GHSA-pwp9-3h93-h2x8 (GitHub Security Advisories)Source: ENISA EUVD
8.1EG
EchelonGraph verdictPlan mitigationNo fix is confirmed yet: check the vendor's advisory for a fixed release; until one is applied, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule (the SSVC decision on this page).
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 8.1Exploit: None knownExposed services: Not assessed
No fix is confirmed yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for the fix.
The CVE record's CNA (Red Hat, Inc.) lists Samba versions 4.25.0 up to but not including 4.25.1 as affected. No release containing a fix is confirmed on record.
- CVSS v3
- 8.1
- EG Score
- 8.1HIGHhigh confidence
- EG Risk
- 37EG Risk 37/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity81% × 45%Impact severity (EG Severity): CVSS 8.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.7% × 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: No fix is confirmed yet. Check the vendor's advisory for a fixed release; until one is applied, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule. - EPSS PROB
- 0.6%
- EPSS %ILE
- 51st
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (8.1): severity, escalated by confirmed exploitation. This CVE's 8.1 is its impact severity (EG Severity), not escalated.
- EG Severity
- 8.1 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.6% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-29). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says. In the directive's words, “Fix on system upgrade” means that, “unless conditions change”, the vulnerability “should be remediated the next time the vulnerable asset receives a scheduled major upgrade or rebuild”: its timelines are “dynamic as facts change”, and a KEV listing shortens them.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
No fix is confirmed yet. Check the vendor's advisory for a fixed release; until one is applied, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule.
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.
No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says. In the directive's words, “Fix on system upgrade” means that, “unless conditions change”, the vulnerability “should be remediated the next time the vulnerable asset receives a scheduled major upgrade or rebuild”: its timelines are “dynamic as facts change”, and a KEV listing shortens them.
The score's inputs: 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
October 28, 2026
Last Modified
October 30, 2026
Advisory Details (5)
Auto-updated Oct 28, 2026No fix on record yet. Sources: redhat.
Web page
16276 – (CVE-2026-109411) CVE-2026-109411: Access control bypass via vfs_ceph_rgw case-insensitive open
https://bugzilla.samba.org/show_bug.cgi?id=16276Red Hat
2552136 – (CVE-2026-109411) CVE-2026-109411 samba: Access control bypass via vfs_ceph_rgw case-insensitive open
https://bugzilla.redhat.com/show_bug.cgi?id=2552136Red HatMentions a patch (unverified)
CVE-2026-109411 - Red Hat Customer Portal
Affected: Red Hat Enterprise Linux 8 or OpenShift Container Platform 4, is affected by this vulnerability and a fix may be released to a
https://access.redhat.com/security/cve/CVE-2026-109411Vendor Advisories for CVE-2026-109411(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 20× in last 7d / 20× 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.
- 2026-11-01 16:33 UTCEPSS rescoreEPSS 0.6% · 51st percentile
- 2026-10-31 16:31 UTCEPSS rescoreEPSS 0.6% · 51st percentile
- 2026-10-30 16:33 UTCEPSS rescoreEPSS 0.6% · 51st percentile
- 2026-10-30 05:26 UTCEG score recompute
- 2026-10-30 05:26 UTCGHSA enrichmentGHSA-pwp9-3h93-h2x8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-10-30 05:15 UTCEG score recompute
- 2026-10-30 05:15 UTCGHSA enrichmentGHSA-pwp9-3h93-h2x8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-10-29 21:26 UTCEG score recompute
- 2026-10-29 21:26 UTCGHSA enrichmentGHSA-pwp9-3h93-h2x8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-10-29 21:01 UTCEG score recompute
- 2026-10-29 21:01 UTCGHSA enrichmentGHSA-pwp9-3h93-h2x8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-10-29 17:27 UTCEG score recompute
- 2026-10-29 17:27 UTCGHSA enrichmentGHSA-pwp9-3h93-h2x8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-10-29 16:42 UTCEG score recompute
- 2026-10-29 16:42 UTCGHSA enrichmentGHSA-pwp9-3h93-h2x8 · GitHub severity HIGH · GitHub CVSS 8.1
- 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.6% · 51st percentile
- 2026-10-28 20:27 UTCEG score recompute
- 2026-10-28 20:01 UTCENISA EUVD ID recordedEUVD-2026-112398 · Source: ENISA EUVD
- 2026-10-28 19:23 UTCEG score recomputeFirst assessed: 8.1 HIGH
- 2026-10-28 19:23 UTCMITRE cvelistV5first tracked
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Frequently asked(5)
What is CVE-2026-109411?
CVE-2026-109411 is a high-severity vulnerability; its CVE record was published on October 28, 2026. An access control bypass flaw was identified in Samba's vfs_ceph_rgw module in it's openat() function. An authenticated user can bypass access controls to read or overwrite restricted files on shares configured with the experimental vfs_ceph_rgw module. When a client requests an existing file using…
When was CVE-2026-109411 made public?
CVE-2026-109411 was made public on October 23, 2026: that is the date its CVE record's CNA, Red Hat, Inc., gives for when the vulnerability was made public. The CVE record itself was published on October 28, 2026. EchelonGraph's copy of the record carries a last-modified date of October 30, 2026; the record at its source may have been updated since.
Is CVE-2026-109411 actively exploited?
CVE-2026-109411 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (51st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-109411?
CVE-2026-109411 has a CVSS base score of 8.1 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-109411?
No fix for CVE-2026-109411 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The CVE record's CNA (Red Hat, Inc.) lists Samba versions 4.25.0 up to but not including 4.25.1 as affected. No release containing a fix is confirmed on record. The vendor advisories EchelonGraph has for CVE-2026-109411 are linked in the Vendor Advisories panel on this page.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-109411
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