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No exploitation reported

CVE-2026-99110

smb: client: fix heap overflow in cifs_do_set_acl()

No exploitation reported by the sources we read.

  • Published2026-10-28

Am I affected?

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Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix heap overflow in cifs_do_set_acl() cifs_set_acl() validates ACL size using posix_acl_xattr_size(): 4 + (count * 8) // 4-byte header + 8 bytes per ACE cifs_do_set_acl() then calls posix_acl_to_cifs() to write the CIFS wire format into the same buffer: 6 + (count * 10) // 6-byte header + 10 bytes per ACE An ACL that passes the xattr-based check in cifs_set_acl() can overflow the heap when posix_acl_to_cifs() writes the larger CIFS format. Validate the CIFS format size against the remaining buffer space and USHRT_MAX before converting--data_count is __u16, so sizes above USHRT_MAX truncate the on-wire packet length, causing the server to apply a partial ACL. Replace MaxDataCount = 1000 with min(CIFSMaxBufSize, USHRT_MAX).

Timeline

dates in UTC
  1. 2026-10-2811:17CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-31 15:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-99110?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-99110?format=csv
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Versions per branch

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

  • CVE-2026-99110 Red Hat Product Security185 known affected

    kernel: smb: client: fix heap overflow in cifs_do_set_acl()

    kernel as a component of Red Hat Enterprise Linux 10 · kernel-64k as a component of Red Hat Enterprise Linux 10 · kernel-64k-core as a component of Red Hat Enterprise Linux 10 · +182 more

Full record on NVD

Fix

  1. No fix available, says the vendor Red Hat Product Security CVE-2026-99110 · 185 productsAffected

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • NVDCVE recordread 2026-10-31
  • CNACVSS 3.17read 2026-10-31
  • FIRST EPSSEPSS score0.2 %2026-10-30

Technical details

CVSS v3 Vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Published
2026-10-28
Last Modified
2026-10-31
NVD status
Received

Frequently asked questions

What is CVE-2026-99110?

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix heap overflow in cifs_do_set_acl() cifs_set_acl() validates ACL size using posix_acl_xattr_size(): 4 + (count * 8) // 4-byte header + 8 bytes per ACE cifs_do_set_acl() then calls posix_acl_to_cifs() to write the CIFS wire format into the same buffer: 6 + (count * 10) // 6-byte header + 10 bytes per ACE An ACL that passes the xattr-based check in cifs_set_acl() can overflow the heap when posix_acl_to_cifs() writes the larger CIFS format. Validate the CIFS format size against the remaining buffer space and USHRT_MAX before converting--data_count is __u16, so sizes above USHRT_MAX truncate the on-wire packet length, causing the server to apply a partial ACL. Replace MaxDataCount = 1000 with min(CIFSMaxBufSize, USHRT_MAX).

Is CVE-2026-99110 actively exploited?

Active exploitation of CVE-2026-99110 has not been confirmed. Its EPSS score was 0.2% on 2026-10-30, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-99110?

CVE-2026-99110 has a CVSS v3 base score of 7 (HIGH severity), with vector string CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.

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