CVE-2026-98405 (GCVE-0-2026-98405)

Vulnerability from cvelistv5 – Published: 2026-10-14 13:27 – Updated: 2026-10-24 14:08
VLAI
Title
smb: client: fix missing iov bounds check in parse_posix_sids()
Summary
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix missing iov bounds check in parse_posix_sids() In parse_posix_sids(), sidsbuf_end is calculated using the server-supplied out_len without being validated against the actual length of the received iov (iov_len). If a server provides an inflated out_len, sidsbuf_end will point past the end of the iov. This defeats the bounds guards in posix_info_sid_size(), allowing out-of-bounds reads into adjacent kernel memory. Fix this by rejecting responses where the calculated sidsbuf_end would exceed the received iov boundaries or cause pointer wraparound.
Severity
8.1 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6649 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: a90f37e3d7acfd9824f162830583bbf7846fe252 , < d91b9a3b2b38e5ac1b51e9e5b23fe53ad7b49644 (git)
Affected: 858e74876c5cbff1dfd5bace99e32fbce2abd4b5 , < b862996e5105be1293da9cdc85da77b76021c3bd (git)
Affected: 858e74876c5cbff1dfd5bace99e32fbce2abd4b5 , < 2f8ed71aaaba3bc8b19cd9930cc62e63e142b299 (git)
Affected: 858e74876c5cbff1dfd5bace99e32fbce2abd4b5 , < eac6917a42899aad0617bbf04798c5dd946a1fe5 (git)
Affected: 858e74876c5cbff1dfd5bace99e32fbce2abd4b5 , < b09d092eb24ad0110f16a9b7c1ed5d2a0c1733dc (git)
Affected: 6.6.32 , < 6.6.158 (semver)
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Linux Linux Affected: 6.8
Unaffected: 0 , < 6.8 (semver)
Unaffected: 6.6.158 , ≤ 6.6.* (semver)
Unaffected: 6.12.112 , ≤ 6.12.* (semver)
Unaffected: 6.18.54 , ≤ 6.18.* (semver)
Unaffected: 7.2.8 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix missing iov bounds check in parse_posix_sids()\n\nIn parse_posix_sids(), sidsbuf_end is calculated using the server-supplied\nout_len without being validated against the actual length of the received\niov (iov_len).\n\nIf a server provides an inflated out_len, sidsbuf_end will point past the\nend of the iov. This defeats the bounds guards in posix_info_sid_size(),\nallowing out-of-bounds reads into adjacent kernel memory.\n\nFix this by rejecting responses where the calculated sidsbuf_end would\nexceed the received iov boundaries or cause pointer wraparound."
        }
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            "version": "3.1"
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              "value": "AV:N - A malicious SMB server supplies the malformed OutputBufferLength and SID payload in an SMB2 QUERY_INFO response over TCP; cifs_root_iget() or cifs_getattr() reaches smb2_query_path_info(), smb2_compound_op(), then parse_posix_sids().\nAC:L - The server can place a valid SID header at the iov boundary and set num_subauth so parse_posix_sids() copies up to 68 bytes beyond it. Once the POSIX mount exists, triggering is deterministic and requires no race or uncontrollable heap state.\nPR:N - Session setup and tree connect precede compound_send_recv(), but the attacker is the SMB server endpoint and needs no account or capability on the client to choose the QUERY_INFO response.\nUI:R - The victim must mount the attacker-controlled share with the posix option, which sets ctx-\u003elinux_ext; cifs_read_super() then calls cifs_root_iget(), which immediately issues the vulnerable POSIX metadata query.\nS:U - The out-of-bounds access occurs in the SMB client and affects the same host kernel executing parse_posix_sids(); it crosses no VM, IOMMU, or sandbox security boundary.\nC:H - An inflated end pointer defeats posix_info_sid_size() bounds checks, allowing each owner or group SID memcpy() to consume up to 68 bytes of adjacent kernel memory and pass those bytes into SID/idmap processing.\nI:N - posix_info_sid_size() caps num_subauth at 15, so each memcpy() remains within its destination struct smb_sid; the defect performs out-of-bounds reads but provides no out-of-bounds write or control-flow modification.\nA:H - By ending the received iov at a SID header while claiming a larger OutputBufferLength, the server makes posix_info_sid_size() and memcpy() access beyond the receive allocation, which can fault and oops or panic the client kernel."
            }
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}



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