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CVE-2026-53390— ksmbd: fix out-of-bounds read in smb_check_perm_dacl()

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 7.1版本存在安全漏洞，该漏洞源于smb_check_perm_dacl()函数在比较SID时未验证ACE大小是否足够包含子授权数量，导致堆越界读取。

CVSS 8.1 · High EPSS 0.47% · P39

Affected Version Matrix 23

VendorProduct Version RangeStatus
Linux Linux 282cbbb476b9f35793452bc461934af4c7eca169< c7488c85fd822959e9b5c22fbd9e7c8a21caf5e0 affected
f20adc4ef7428bc485ee83fd1a592252fb87718b< 988c93d3bba066d8669143e6ec30bb2be9608d53 affected
325d4ac11f526cb8964cff14548ccf02d8c756d8< 36599894fa8536fefdf1e296c0af71b8b7226859 affected
95e5aa3c3261da8c95b27d7aecf8ee39b9f86a4c< d5c81a095c86fe507c032d08f3a8cfc518444927 affected
90089584b2e25c4510b7b987387b4405f0673ece< 7627ff8c4f9919f14de562b0160ab4ec9d80b1f7 affected
d07b26f39246a82399661936dd0c853983cfade7< e36e35660adb9b8ef1435ac359151dda5f094c55 affected
d07b26f39246a82399661936dd0c853983cfade7< 1ef06004ed4bd6d3ed8c840d9d1a376b66d4935b affected
151b1799861fde38087c08f613abc2843ef597b0 affected
… +15 more rows
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I. Basic Information for CVE-2026-53390

Vulnerability Information
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Vulnerability Title
ksmbd: fix out-of-bounds read in smb_check_perm_dacl()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix out-of-bounds read in smb_check_perm_dacl() The permission-check ACE walk in smb_check_perm_dacl() validates the ACE header size and caps sid.num_subauth at SID_MAX_SUB_AUTHORITIES, but it never checks that ace->size is actually large enough to contain num_subauth sub-authorities before compare_sids() dereferences them. CIFS_SID_BASE_SIZE covers the SID header up to but excluding the sub_auth[] array, and offsetof(struct smb_ace, sid) is the ACE header, so the existing guards only guarantee the 8-byte SID base, i.e. zero sub-authorities. compare_sids() then reads ace->sid.sub_auth[i] for i < min(local_sid->num_subauth, ace->sid.num_subauth). The local comparison SIDs (sid_everyone, sid_unix_NFS_mode, and the id_to_sid() result) always have at least one sub-authority, and an attacker controls the ACE revision and authority bytes (which lie within the in-bounds SID base), so they can match one of those SIDs and force the sub_auth read. A crafted ACE with size == 16 and num_subauth >= 1 placed at the tail of the security descriptor therefore causes a heap out-of-bounds read of up to SID_MAX_SUB_AUTHORITIES * sizeof(__le32) bytes past the pntsd allocation. The security descriptor is loaded by ksmbd_vfs_get_sd_xattr() into a buffer sized exactly to the on-disk data (kzalloc(sd_size) in ndr_decode_v4_ntacl()), so the read lands past the allocation. The malformed descriptor can be stored verbatim via SMB2_SET_INFO (the DACL is not normalised before being written to the security.NTACL xattr) and the read fires on a subsequent SMB2_CREATE access check, making this reachable by an authenticated client on a share that uses ACL xattrs. Add the missing num_subauth-versus-ace_size check, mirroring the identical guards already present in the sibling parsers parse_dacl() and smb_inherit_dacl().
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 7.1版本存在安全漏洞，该漏洞源于smb_check_perm_dacl()函数在比较SID时未验证ACE大小是否足够包含子授权数量，导致堆越界读取。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 282cbbb476b9f35793452bc461934af4c7eca169 ~ c7488c85fd822959e9b5c22fbd9e7c8a21caf5e0 -
Linux Linux 7.1 -

II. Public POCs for CVE-2026-53390

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III. Intelligence Information for CVE-2026-53390

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Patches & Fixes for CVE-2026-53390 (6)

Same Patch Batch · Linux · 2026-07-19 · 429 CVEs total

CVE-2026-63795 10.0 CRITICAL 9p: avoid putting oldfid in p9_client_walk() error path
CVE-2026-64089 9.8 CRITICAL batman-adv: tt: fix negative last_changeset_len
CVE-2026-53398 9.8 CRITICAL NFSD: Fix SECINFO_NO_NAME decode error cleanup
CVE-2026-63984 9.8 CRITICAL ipv6: rpl: fix hdrlen overflow in ipv6_rpl_srh_decompress()
CVE-2026-64025 9.8 CRITICAL bpf, skmsg: fix verdict sk_data_ready racing with ktls rx
CVE-2026-63979 9.8 CRITICAL net/handshake: hand off the pinned file reference to accept_doit
CVE-2026-63924 9.8 CRITICAL ipv6: exthdrs: refresh nh pointer after ipv6_hop_jumbo()
CVE-2026-64056 9.8 CRITICAL net: ethernet: cortina: Make RX SKB per-port
CVE-2026-63800 9.8 CRITICAL pNFS: Fix use-after-free in pnfs_update_layout()
CVE-2026-63978 9.8 CRITICAL net/handshake: Drain pending requests at net namespace exit
CVE-2026-64055 9.8 CRITICAL net: ethernet: cortina: Carry over frag counter
CVE-2026-63808 9.8 CRITICAL exfat: fix potential use-after-free in exfat_find_dir_entry()
CVE-2026-64033 9.8 CRITICAL RDMA/rtrs: Fix use-after-free in path file creation cleanup
CVE-2026-63888 9.8 CRITICAL scsi: target: iscsi: Fix CRC overread and double-free in iscsit_handle_text_cmd()
CVE-2026-63887 9.8 CRITICAL scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf
CVE-2026-64113 9.8 CRITICAL ixgbevf: fix use-after-free in VEPA multicast source pruning
CVE-2026-64162 9.8 CRITICAL idpf: fix read_dev_clk_lock spinlock init in idpf_ptp_init()
CVE-2026-63922 9.8 CRITICAL ipv6: exthdrs: refresh nh after handling HAO option
CVE-2026-64035 9.8 CRITICAL igc: set tx buffer type for SMD frames
CVE-2026-63886 9.8 CRITICAL scsi: target: iscsi: Validate CHAP_R length before base64 decode

Showing top 20 of 429 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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