CVE-2015-0240: The 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

Q: How do I fix CVE-2015-0240?

enterprise linux: mitigate or apply the listed mitigation; samba: downgrade or apply the listed mitigation; suse linux enterprise desktop: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2015-0240 being exploited?

CVE-2015-0240 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2015-0240 affect?

CVE-2015-0240 affects enterprise linux, samba, suse linux enterprise desktop. Severity is high (CVSS 10.0). The 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 before 4.2.0rc5 performs a free operation on an uninitialized stack pointer, which allows remote attacker

Q: How urgent is CVE-2015-0240?

Priority 70/100. Critical severity; EPSS top 1%: very likely to be exploited; Public exploit reference; On your watchlist

This week

HIGH 10.0WATCHLISTMITIGATEDOWNGRADEMITIGATE

CVE-2015-0240 is a high-severity flaw (CVSS 10.0) affecting enterprise linux, samba, suse linux enterprise desktop. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The 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 before 4.2.0rc5 performs a free operation on an uninitialized stack pointer, which allows remote attackers to execute arbitrary code via crafted Netlogon packets that use the ServerPasswordSet RPC API, as demonstrated by packets reaching the _netr_ServerPasswordSet function in rpc_server/netlogon/srv_netlog_nt.c.

Why this priority

Critical severity
EPSS top 1%: very likely to be exploited
Public exploit reference
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	10.0 (High)
EPSS exploit chance	88.2% (top 1%)
CISA exploited list	No
Weakness	CWE-17
Published	2015-02-24
Last modified	2026-06-17

Publisher (CNA): Red Hat, Inc. · Vendor: canonical · novell · redhat · samba

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2015-02-24 01:59 UTCPublished CVE record published
2026-06-17 00:19 UTCUpdated Record last modified

redhat enterprise linux MITIGATE

Affected: 5 · 6.0 · 7.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 5

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

samba samba DOWNGRADE

Affected: 3.5.0 · 3.5.1 · 3.5.2 · 3.5.3 · 3.5.4 · 3.5.5 · 3.5.6 · 3.5.7

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.5.0

1. Check installed version

apt-cache policy samba || rpm -q samba || samba --version

2. No fixed release: DOWNGRADE to a release before 3.5.0 (Debian / Ubuntu)

apt-cache madison samba sudo apt install samba=<VERSION_BEFORE_3.5.0> sudo apt-mark hold samba

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list samba sudo dnf downgrade samba-<VERSION_BEFORE_3.5.0> sudo dnf versionlock add samba

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

novell suse linux enterprise desktop MITIGATE

Affected: 12

Fixed in: no fixed release known

Safe to downgrade to: a release before 12

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

novell suse linux enterprise server MITIGATE

Affected: 12

Fixed in: no fixed release known

Safe to downgrade to: a release before 12

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

novell suse linux enterprise software development kit MITIGATE

Affected: 12

Fixed in: no fixed release known

Safe to downgrade to: a release before 12

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

canonical ubuntu linux MITIGATE

Affected: 12.04 · 14.04 · 14.10

Fixed in: no fixed release known

Safe to downgrade to: a release before 12.04

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora 46 · rust-tokio · FIXED · 1.54.1-1.fc46 · FEDORA-2026-e7fd815169 · source

sudo dnf upgrade --advisory=FEDORA-2026-e7fd815169

Fedora ELN · libopenraw · FIXED · 0.3.7-2.eln159 · FEDORA-2026-3fa115dd38 · source

sudo dnf upgrade --advisory=FEDORA-2026-3fa115dd38

Debian 12 · samba · FIXED · 2:4.1.17+dfsg-1

sudo apt update && sudo apt install --only-upgrade samba dpkg --compare-versions "$(dpkg-query -W -f='${Version}' samba)" ge "2:4.1.17+dfsg-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · samba · FIXED · 2:4.1.17+dfsg-1

sudo apt update && sudo apt install --only-upgrade samba dpkg --compare-versions "$(dpkg-query -W -f='${Version}' samba)" ge "2:4.1.17+dfsg-1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 5 · samba3x · FIXED · samba3x-3.6.23-9.el5_11

sudo dnf upgrade --advisory=RHSA-2015:0249 rpm -q samba3x

RHEL 5.6 Long Life · samba3x · FIXED · samba3x-3.5.4-0.70.el5_6.4

sudo dnf upgrade --advisory=RHSA-2015:0253 rpm -q samba3x

RHEL 5.9 Extended Update Support · samba3x · FIXED · samba3x-3.6.6-0.131.el5_9

sudo dnf upgrade --advisory=RHSA-2015:0253 rpm -q samba3x

RHEL 6 · samba4 · FIXED · samba4-4.0.0-66.el6_6.rc4

sudo dnf upgrade --advisory=RHSA-2015:0250 rpm -q samba4

RHEL 6 · samba · FIXED · samba-3.6.23-14.el6_6

sudo dnf upgrade --advisory=RHSA-2015:0251 rpm -q samba

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: securityblog.redhat.com/2015/02/23/samba-vulnerability-cve-2015-0240/
Write-up: www.exploit-db.com/exploits/36741/
Exploit-DB: Samba < 3.6.2 (x86) - Denial of Service (PoC)
Metasploit: Samba _netr_ServerPasswordSet Uninitialized Credential State

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2015-0240?

enterprise linux: mitigate or apply the listed mitigation; samba: downgrade or apply the listed mitigation; suse linux enterprise desktop: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2015-0240 being exploited?

CVE-2015-0240 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2015-0240 affect?

CVE-2015-0240 affects enterprise linux, samba, suse linux enterprise desktop. Severity is high (CVSS 10.0). The 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 before 4.2.0rc5 performs a free operation on an uninitialized stack pointer, which allows remote attacker

How urgent is CVE-2015-0240?

Priority 70/100. Critical severity; EPSS top 1%: very likely to be exploited; Public exploit reference; On your watchlist

Software pages

Ubuntu vulnerabilities · Samba vulnerabilities

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References

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