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CVE-2018-16841· NVD / CVE Program· CNA redhat

Samba from version 4.3.0 and before versions 4.7.12, 4.8.7 and 4.9.3 are vulnerable to a denial of service.

Samba from version 4.3.0 and before versions 4.7.12, 4.8.7 and 4.9.3 are vulnerable to a denial of service. When configured to accept smart-card authentication, Samba's KDC will call talloc_free() twice on the same memory if the principal in a validly signed certificate does not match the principal in the AS-REQ. This is only possible after authentication with a trusted certificate. talloc is robust against further corruption from a double-free with talloc_free() and directly calls abort(), terminating the KDC process.

MediumCVSS 6.5 · v3.1—No exploit Fix available
Published
Nov 28, 2018
Updated
Jun 16, 2026
EPSS
4.6% · 91th percentile
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Report tools

JSON

Action score

27

Monitor

Low priority for now.

CVSS
26 / 40 · 6.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 4.6%

CNA vs NVD score

NVD
6.5
CNA · redhat
5.7
0.8 point gap

CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Affected systems

VendorProduct
sambasamba
canonicalubuntu linux
debiandebian linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • canonical ubuntu linux12.04
  • canonical ubuntu linux14.04
  • canonical ubuntu linux16.04
  • canonical ubuntu linux18.04
  • canonical ubuntu linux18.10
  • debian debian linux9.0
  • samba samba4.9.0 and later · before 4.9.3
  • samba samba4.8.0 and later · before 4.8.7
  • samba samba4.3.0 and later · before 4.7.12

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.

  • [UNKNOWN] samba

    • 4.7.12, 4.8.7, 4.9.3affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Alpine:v3.10sambafrom 4.3.0 · before 4.8.7-r04.8.7-r0
Alpine:v3.6sambafrom 4.3.0 · before 4.6.16-r24.6.16-r2
Alpine:v3.7sambafrom 4.3.0 · before 4.7.6-r24.7.6-r2
Alpine:v3.8sambafrom 4.3.0 · before 4.8.8-r04.8.8-r0
Debian:12sambabefore 2:4.9.2+dfsg-22:4.9.2+dfsg-2
Debian:9sambabefore 2:4.5.12+dfsg-2+deb9u42:4.5.12+dfsg-2+deb9u4
SUSE:Linux Enterprise Module for Basesystem 15sambabefore 4.7.11+git.140.6bd0e5b30d8-4.21.14.7.11+git.140.6bd0e5b30d8-4.21.1

Same product

samba: all records

Other 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 cliKEV
    99Now
  • 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 befor
    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, al
    66This week
  • CVE-2003-0201Buffer overflow in the call_trans2open function in trans2.c for Samba 2.2.x before 2.2.8a, 2.0.10 and earlier 2.0.x versions, and Samba-TNG
    65This week
  • CVE-2007-2446Multiple heap-based buffer overflows in the NDR parsing in smbd in Samba 3.0.0 through 3.0.25rc3 allow remote attackers to execute arbitrary
    63This week
  • CVE-2012-1182The RPC code generator in Samba 3.x before 3.4.16, 3.5.x before 3.5.14, and 3.6.x before 3.6.4 does not implement validation of an array len
    62This week

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
alpine:samba4.8.7-r0 · Alpine:v3.10Package registry (OSV)
debian:samba2:4.9.2+dfsg-2 · Debian:12Package registry (OSV)
suse:samba4.7.11+git.140.6bd0e5b30d8-4.21.1 · SUSE:Linux Enterprise Module for Basesystem 15Package registry (OSV)

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.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

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 researchers

Finders, 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.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

c
free(dev->buf);/* ... another thread is still running ... */process(dev->buf);

Fixed

c
lock(&dev->lock);free(dev->buf);dev->buf = NULL;unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

We use this product, ask for help

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records