USN-8621-1: Samba vulnerabilities
It was discovered that Samba's pam_winbind incorrectly handled home directory ownership when mkhomedir was enabled. A local attacker could possibly use this issue to cause a denial of service by triggering a change in ownership of the root directory. (CVE-2026-15779) Arjun Basnet, Douglas Bagnall, and Andrew Tridgell discovered that Samba incorrectly handled TSIG packets with name compression. A remote attacker could possibly use this issue to cause Samba to crash, resulting in a denial of service. (CVE-2026-6949) Tristan Madani discovered that Samba incorrectly handled malformed ASN.1 kpasswd packets. An authenticated user could possibly use this issue to cause Samba to crash, resulting in a denial of service. (CVE-2026-58216) Andrew Tridgell and Tristan Madani discovered that Samba incorrectly handled TKEY name registration. A remote attacker could possibly use this issue to exhaust the TKEY name cache, resulting in a denial of service. (CVE-2026-58218) It was discovered that Samba incorrectly handled internal LDB special directory names when processing authenticated LDAP requests. An authenticated user could possibly use this issue to perform unauthorized modifications and gain control of a domain. (CVE-2026-58221) Andrew Tridgell and Tristan Madani discovered that Samba incorrectly handled LDAP Compare requests. An authenticated user could possibly use this issue to obtain sensitive information. (CVE-2026-58222) Tristan Madani, Andrew Tridgell, and Martin Schwenke discovered that the CTDB protocol in Samba had insufficient bounds checking. A remote attacker could possibly use this issue to cause Samba to crash, resulting in a denial of service. (CVE-2026-58224)
CSIRTS triage
- What
- Samba has vulnerabilities that can lead to denial of service under certain conditions.
- Who is affected
- Local and remote attackers can exploit these vulnerabilities in Samba installations.
- Urgency
- Remediation is urgent as these vulnerabilities can cause service disruptions, although exploitation status is currently unknown.
- Action
- Users should apply updates to Samba to address these vulnerabilities.
AI-assisted analysis generated from the source advisory — verify against the original.
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Details
Original advisory: https://ubuntu.com/security/notices/USN-8621-1
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Low exploitation riskCVE-2026-157790.10% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 1% of all scored CVEs.
- Low exploitation riskCVE-2026-582160.52% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 41% of all scored CVEs.
- Moderate exploitation riskCVE-2026-582181.1% 30-day exploitation probability. Patch within normal cadence, watch for KEV listing. Riskier than 62% of all scored CVEs.
- Low exploitation riskCVE-2026-582220.84% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 54% of all scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-15779 | coverage & exploitation status | NVD · CVE.org |
| CVE-2026-6949 | coverage & exploitation status | NVD · CVE.org |
| CVE-2026-58216 | coverage & exploitation status | NVD · CVE.org |
| CVE-2026-58218 | coverage & exploitation status | NVD · CVE.org |
| CVE-2026-58221 | coverage & exploitation status | NVD · CVE.org |
| CVE-2026-58222 | coverage & exploitation status | NVD · CVE.org |
| CVE-2026-58224 | coverage & exploitation status | NVD · CVE.org |
Same CVEs, other sources
How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.
- high[NEW] [high] Samba: Multiple vulnerabilitiescert-bund
- highCVE-2026-58222: A security flaw combining LDAP filter injection and improper authorization checks was found in…nvd
- mediumCVE-2026-58216: An out-of-bounds read flaw was found in Samba's Kerberos Key Distribution Center's (KDC) passw…nvd
- mediumCVE-2026-58218: A flaw was found in Samba's internal DNS server where unauthenticated TKEY registration reques…nvd
- medium[NEW] [UNPATCHED] [medium] Samba: Vulnerability allows Denial of Servicecert-bund
- unknownMultiple vulnerabilities in Samba (July 28, 2026)cert-fr-avis
- unknownDSA-6401-1 samba - security updatedebian
- mediumCVE-2026-15779: A flaw was found in samba's pam_winbind. When mkhomedir is enabled, pam_winbind chowns the tar…nvd
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