CVE-2017-7494 — samba
CRITICALCVE-2017-7494 is a critical-severity (CVSS 9.8) Code Injection vulnerability. It is in CISA's Known Exploited Vulnerabilities catalog (added 2023-03-30) and has been used in ransomware campaigns — treat it as actively exploited and patch now. A fix is available — see the affected versions and patch details below.
Exploitation Status
Actively exploited in the wild
- Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2023-03-30 — including use in ransomware campaigns. Federal agencies were required to remediate by 2023-04-20.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2017-7494.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2017-7494 by exploitation likelihood (EPSS) against impact (CVSS). In the shaded patch-first corner (EPSS 50%+, CVSS 7.0+).
Where this sits among everything scored
Of 395,249 CVEs with a current EPSS score, this one falls in the ≥ 90% band (highlighted). Counts from FIRST.org, log-scaled.
Description
Samba 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 client to upload a shared library to a writable share, and then cause the server to load and execute it.
Affected Products
debian linuxdebiansambasambaResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Samba 3.5.0 - Remote Code Execution
by steelo · May 24, 2017
Samba 3.5.0 < 4.4.14/4.5.10/4.6.4 - 'is_known_pipename()' Arbitrary Module Load (Metasploit)
by Metasploit · May 29, 2017
Detection & mitigation playbook
VulnerabilityDetect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Fix
Upgrade the affected component to the fixed release for CVE-2017-7494, or apply your distribution's backported patch — distro builds are often patched at an older version number, so check your vendor's advisory rather than the upstream version alone.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This vulnerability exists in the samba server, client side packages are not affected.
Any of the following: 1. SELinux is enabled by default and our default policy prevents loading of modules from outside of samba's module directories and therefore blocks the exploit 2. Mount the filesystem which is used by samba for its writable share using "noexec" option. 3. Add the parameter: nt pipe support = no to the [global] section of your smb.conf and restart smbd. This prevents clients from accessing any named pipe endpoints. Note this can disable some expected functionality for Windows clients.Source: Red Hat security advisory for CVE-2017-7494 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 5 Extended Lifecycle Support | samba3x-0:3.6.23-14.el5_11 | RHSA-2017:1272 |
| Red Hat Enterprise Linux 6 | samba-0:3.6.23-43.el6_9 | RHSA-2017:1270 |
| Red Hat Enterprise Linux 6 | samba4-0:4.2.10-10.el6_9 | RHSA-2017:1271 |
| Red Hat Enterprise Linux 6.2 Advanced Update Support | samba-0:3.6.23-32.el6_2 | RHSA-2017:1390 |
| Red Hat Gluster Storage 3.2 for RHEL 6 | samba-0:4.4.6-5.el6rhs | RHSA-2017:1273 |
Frequently Asked Questions
Is CVE-2017-7494 in your dependencies?
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