CVE-2021-20316: A flaw was found in the way Samba handled file/directory metadata.
Noroxi assessment
Priority: Monitor (action score 27/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 1.1% (FIRST EPSS); higher than 66.1% of all records.
- Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. Special conditions such as timing or configuration are required.
- Fixed version: Azure Linux 3.0 ARM 4.18.3-1; Azure Linux 3.0 x64 4.18.3-1.
Low priority for now. Upgrade to Azure Linux 3.0 ARM 4.18.3-1; Azure Linux 3.0 x64 4.18.3-1 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
A flaw was found in the way Samba handled file/directory metadata. This flaw allows an authenticated attacker with permissions to read or modify share metadata, to perform this operation outside of the share.
- Published
- Aug 23, 2022
- Updated
- Jun 16, 2026
- EPSS
- 1.1% · 66th percentile
- CWE
- CWE-362
Report tools
Action score
27
Low priority for now.
- CVSS
- 27 / 40 · 6.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 1.1%
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
Is your version affected? Check itNoroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| samba | samba | cpe:2.3:a:samba:samba |
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
| redhat | virtualization host | cpe:2.3:a:redhat:virtualization_host |
| redhat | enterprise linux | cpe:2.3:o:redhat:enterprise_linux |
| redhat | enterprise linux aus | cpe:2.3:o:redhat:enterprise_linux_aus |
| redhat | enterprise linux eus | cpe:2.3:o:redhat:enterprise_linux_eus |
| redhat | enterprise linux tus | cpe:2.3:o:redhat:enterprise_linux_tus |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- debian debian linux10.0
- debian debian linux11.0
- redhat enterprise linux8.0
- redhat enterprise linux aus8.6
- redhat enterprise linux eus8.6
- redhat enterprise linux tus8.6
- redhat virtualization host4.0
- samba sambabefore 4.15.0
Versions reported by the vendor
Affected version ranges reported by the assigning authority (redhat). Independent of NVD's CPE analysis and usually ahead of it.
n/a samba
- Affects samba file server before v4.15.0, Fixed in samba v4.15.0affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:8 | ctdb | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | libsmbclient | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | libsmbclient-devel | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | libwbclient | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | libwbclient-devel | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | libwbclient-devel | before 4.15.5-8.el8_6 | 4.15.5-8.el8_6 |
| AlmaLinux:8 | python3-samba | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | python3-samba-test | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | samba | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | samba-client | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | samba-client-libs | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | samba-common | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | samba-common-libs | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | samba-common-tools | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | samba-devel | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | samba-krb5-printing | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | samba-libs | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | samba-pidl | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | samba-test | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | samba-test-libs | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | samba-vfs-iouring | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | samba-winbind | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | samba-winbind-clients | before 4.15.5-5.el8 | 4.15.5-5.el8 |
| AlmaLinux:8 | samba-winbind-krb5-locator | before 4.15.5-5.el8 | 4.15.5-5.el8 |
+96
Same product
samba: all recordsOther highest-scoring records for the same primary product.
- CVE-2017-7494Samba since version 3.5.0 and before 4.6.4, 4.5.10 and 4.4.14 is vulnerable to remote code execution vulnerability, allowing a malicious…KEV99Now
- CVE-2015-0240The Netlogon server implementation in smbd in Samba 3.5.x and 3.6.x before 3.6.25, 4.0.x before 4.0.25, 4.1.x before 4.1.17, and 4.2.x…66This week
- CVE-2003-0085Buffer overflow in the SMB/CIFS packet fragment re-assembly code for SMB daemon (smbd) in Samba before 2.2.8, and Samba-TNG before 0.3.1…66This week
Published before and after this one in the same product
- ← EarlierCVE-2021-3738Mar 2, 2022 · In DCE/RPC it is possible to share the handles (cookies for resource state) between multiple connections via a mechanism called…36Monitor
- ← EarlierCVE-2020-25721Mar 16, 2022 · Kerberos acceptors need easy access to stable AD identifiers (eg objectSid).36Monitor
- Later →CVE-2021-3670Aug 23, 2022 · MaxQueryDuration not honoured in Samba AD DC LDAP27Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Azure Linux 3.0 ARM | 4.18.3-1 · samba | Microsoft (MSRC) |
| Azure Linux 3.0 x64 | 4.18.3-1 · samba | Microsoft (MSRC) |
| almalinux:ctdb | 4.15.5-5.el8 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:libsmbclient | 4.15.5-5.el8 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:libsmbclient-devel | 4.15.5-5.el8 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:libwbclient | 4.15.5-5.el8 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:libwbclient-devel | 4.15.5-8.el8_6 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python3-samba | 4.15.5-5.el8 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python3-samba-test | 4.15.5-5.el8 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:samba | 4.15.5-5.el8 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:samba-client | 4.15.5-5.el8 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:samba-client-libs | 4.15.5-5.el8 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:samba-common | 4.15.5-5.el8 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:samba-common-libs | 4.15.5-5.el8 · AlmaLinux:8 | Package registry (OSV) |
| debian:samba | 2:4.16.0+dfsg-2 · Debian:12 | Package registry (OSV) |
| opensuse:apparmor | 2.13.6-150300.3.11.2 · openSUSE:Leap 15.3 | Package registry (OSV) |
| opensuse:krb5 | 1.19.2-150300.8.3.2 · openSUSE:Leap 15.3 | Package registry (OSV) |
| opensuse:krb5-mini | 1.19.2-150300.8.3.2 · openSUSE:Leap 15.3 | Package registry (OSV) |
| opensuse:ldb | 2.4.1-150300.3.10.1 · openSUSE:Leap 15.3 | Package registry (OSV) |
| opensuse:libapparmor | 2.13.6-150300.3.11.1 · openSUSE:Leap 15.3 | Package registry (OSV) |
| opensuse:samba | 4.15.4+git.324.8332acf1a63-150300.3.25.3 · openSUSE:Leap 15.3 | Package registry (OSV) |
| opensuse:sssd | 1.16.1-150300.23.17.3 · openSUSE:Leap 15.3 | Package registry (OSV) |
| opensuse:talloc | 2.3.3-150300.3.3.2 · openSUSE:Leap 15.3 | Package registry (OSV) |
| opensuse:talloc-man | 2.3.3-150300.3.3.1 · openSUSE:Leap 15.3 | Package registry (OSV) |
| opensuse:tdb | 1.4.4-150300.3.3.2 · openSUSE:Leap 15.3 | Package registry (OSV) |
| opensuse:tevent | 0.11.0-150300.3.3.2 · openSUSE:Leap 15.3 | Package registry (OSV) |
| opensuse:tevent-man | 0.11.0-150300.3.3.1 · openSUSE:Leap 15.3 | Package registry (OSV) |
| red hat:ctdb | 0:4.15.5-100.el8rhgs · Red Hat:storage:3.5:samba:el8 | Package registry (OSV) |
| red hat:ctdb-debuginfo | 0:4.15.5-100.el8rhgs · Red Hat:storage:3.5:samba:el8 | Package registry (OSV) |
| red hat:libsmbclient | 0:4.15.5-100.el8rhgs · Red Hat:storage:3.5:samba:el8 | Package registry (OSV) |
+22
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
No history yet (it accumulates with the daily EPSS job).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- A low-privileged account is enough.
- No user action is required.
- Special conditions such as timing or configuration are required.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- none
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- None
Weakness class (CWE)
CWE-362 · Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')CVSS vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
—
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (5 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.