CVE-2023-4091
No exploitation reported by the sources we read.
- Published2023-11-03
- Fixed in4.19.1 · 4.18.8 · 4.17.12
- WeaknessCWE-276
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
Description
A vulnerability was discovered in Samba, where the flaw allows SMB clients to truncate files, even with read-only permissions when the Samba VFS module "acl_xattr" is configured with "acl_xattr:ignore system acls = yes". The SMB protocol allows opening files when the client requests read-only access but then implicitly truncates the opened file to 0 bytes if the client specifies a separate OVERWRITE create disposition request. The issue arises in configurations that bypass kernel file system permissions checks, relying solely on Samba's permissions.
Timeline
dates in UTC- 2023-11-0308:15CVE publishedNVD
Observed activity
isMalicious corpus · updated 2026-10-23 21:37 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2023-4091?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2023-4091?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
NVD| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 4.19 | ≥ 4.19.0, < 4.19.1 | 4.19.1 | NVD |
| 4.18 | ≥ 4.18.0, < 4.18.8 | 4.18.8 | NVD |
| 4.17 | < 4.17.12 | 4.17.12 | NVD |
| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 39.x | = 39 | no fix published | NVD |
| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 8.0 | = 8.0 | no fix published | NVD |
2 more products in the sources.
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Distribution builds and vendor advisories
Packages from OSV.dev and products from the vendors' CSAF advisories.
version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.
Packages
- sambaAlmaLinux:9all versions · fixed in 4.18.6-101.el9_3.alma.1and 33 other packages
- sambaAlmaLinux:8all versions · fixed in 4.18.6-2.el8_9.alma.1and 33 other packages
Fix
- Update Samba to 4.19.1 · 4.18.8 · 4.17.12
Advisories and patches
- www.samba.orgVendor Advisory
Detection
- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- none listed PoC-in-GitHub
Sources
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
- Published
- 2023-11-03
- Last Modified
- 2026-06-17
- NVD status
- Modified
Frequently asked questions
What is CVE-2023-4091?
Is CVE-2023-4091 actively exploited?
What is the CVSS score for CVE-2023-4091?
Running samba? Hear about its next vulnerability
Surveillance reads the versions in your stack — a domain, a lockfile or a list — checks each CVE against the ranges its sources publish, and alerts you when one you run is exploited or enters CISA KEV. A version it cannot read stays « version not verified ».
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Go further
- Following what attackers exploit right now? The CISA KEV additions of the month, with their patch deadlines.
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Related vulnerabilities
Same product first, then the same vendor advisory and the same publication week.