CVE-2026-4408: Red Hat Enterprise Linux 10 samba · OS Command Injection
Affects Red Hat Enterprise Linux 10 sambaSource CVE Database V5
Not known to be exploited · CVSS 9.0 Critical.
Data as of 30 Oct 2026, 06:59 UTC
- EPSS
- 2.5% chance of exploitation in 30 days – higher than 84% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 28 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
Public exploit code: GitHub proofs of concept
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Red Hatredhat/sambapkg:rpm/redhat/sambaOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Red Hat has released official security updates that fix this vulnerability in Samba for Red Hat Enterprise Linux 10. Users should apply the updates as described in the Red Hat advisories RHSA-2026:22963 and RHSA-2026:22644. The vendor advisory confirms the availability of patches and recommends updating affected Samba packages to the fixed versions. Systems not using the 'check password script' with %u or not running samba-dcerpcd as a system service are less likely to be affected. Patch status is confirmed by Red Hat advisories.
Description
A flaw was found in Samba. A remote attacker can exploit a misconfiguration in Samba file servers and classic domain controllers that use the "check password script" feature. If this script is configured with the %u substitution character, the client-controlled username is passed without proper escaping of shell meta-characters. This vulnerability allows an attacker to achieve remote command execution on the affected system. This issue primarily affects non-standard configurations where the "check password script" is used with %u and the samba-dcerpcd service is started as a system service.
References
- access.redhat.com/errata/RHSA-2026:22644 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:22963 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:25049 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:25979 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:28053 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:28054 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:28055 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:28056 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:28057 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:28058 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:28132 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:29799 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:29833 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:29863 (opens in a new tab)
- access.redhat.com/security/cve/CVE-2026-4408 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2479762 (opens in a new tab)
- bugzilla.samba.org/show_bug.cgi?id=16034 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4408.json (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:57483 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:56786 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:56853 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:56911 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:59831 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:60019 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:65839 (opens in a new tab)