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CVE-2026-64139— ksmbd: fix SID memory leak in set_posix_acl_entries_dacl() on overflow

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存在安全漏洞，该漏洞源于ksmbd的set_posix_acl_entries_dacl()函数对DACL大小溢出处理不当，导致SID内存泄漏，通过恶意文件可导致内核内存耗尽。

AI Predicted 4.0 Difficulty: Easy EPSS 0.17% · P6

Affected Version Matrix 11

VendorProduct Version RangeStatus
Linux Linux 41e53a773db6342ac9a689ee5ba635c31744c9f0< 9b0a8985b419a71ee1cc9c0cc6a9e1bb7815a2c5 affected
8d5729350b236896f51379588d9a690b7fafb8db< 9d378e17c864da08c3a4df41dae92cfa6468b00a affected
e1955a94b6f17f4b058afa955a6f187eb3ed7615< 519fb0a42ce5d7e46935577309fb282a5f2c6ea3 affected
5e7b8f3c539d69b2ed5f2408e2f75e68ce7eef43< 0e198f09cb2a554c04de0fea4e790f1250a943ca affected
ef7902be3f215b6bf7babe4dc9dd9a7d57dad7a7< eced48cb08f07393a5ea770fdd1026452883c3ad affected
299f962c0b02d048fb45d248b4da493d03f3175d< af92ee994cc7f7e83a41c2025f32257a2f82a7ef affected
6.1.175< 6.1.184 affected
6.6.136< 6.6.142 affected
… +3 more rows
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I. Basic Information for CVE-2026-64139

Vulnerability Information
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Vulnerability Title
ksmbd: fix SID memory leak in set_posix_acl_entries_dacl() on overflow
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix SID memory leak in set_posix_acl_entries_dacl() on overflow Commit 299f962c0b02 ("ksmbd: use check_add_overflow() to prevent u16 DACL size overflow") added check_add_overflow() guards that break out of the ACE-building loops in set_posix_acl_entries_dacl() when the accumulated DACL size would wrap past 65535. However, each iteration allocates a struct smb_sid via kmalloc_obj() at the top of the loop and relies on the kfree(sid) call at the end of the loop body (the 'pass_same_sid' label in the first loop, and the explicit kfree at the tail of the second loop) to release it. The newly introduced 'break' statements bypass those kfree() calls, leaking the sid buffer every time an overflow is detected. A malicious or malformed file with enough POSIX ACL entries to trip the overflow check will leak one or more struct smb_sid allocations on every request that touches the file's DACL, providing a trivial kernel memory exhaustion vector. Free sid before breaking out of the loops to plug the leak.
Source: CVE Program / CVE List V5
CVSS Information
N/A
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存在安全漏洞，该漏洞源于ksmbd的set_posix_acl_entries_dacl()函数对DACL大小溢出处理不当，导致SID内存泄漏，通过恶意文件可导致内核内存耗尽。
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 41e53a773db6342ac9a689ee5ba635c31744c9f0 ~ 9b0a8985b419a71ee1cc9c0cc6a9e1bb7815a2c5 -
Linux Linux 6.1.175 ~ 6.1.184 -

II. Public POCs for CVE-2026-64139

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III. Intelligence Information for CVE-2026-64139

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Patches & Fixes for CVE-2026-64139 (5)

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-2026-63887 9.8 CRITICAL scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf
CVE-2026-63994 9.8 CRITICAL tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()
CVE-2026-64035 9.8 CRITICAL igc: set tx buffer type for SMD frames
CVE-2026-64142 9.8 CRITICAL ksmbd: close durable scavenger races against m_fp_list lookups
CVE-2026-63993 9.8 CRITICAL vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()
CVE-2026-53399 9.8 CRITICAL nfsd: release layout stid on setlease failure
CVE-2026-53398 9.8 CRITICAL NFSD: Fix SECINFO_NO_NAME decode error cleanup
CVE-2026-63825 9.8 CRITICAL gcov: use atomic counter updates to fix concurrent access crashes
CVE-2026-64025 9.8 CRITICAL bpf, skmsg: fix verdict sk_data_ready racing with ktls rx
CVE-2026-64033 9.8 CRITICAL RDMA/rtrs: Fix use-after-free in path file creation cleanup
CVE-2026-63886 9.8 CRITICAL scsi: target: iscsi: Validate CHAP_R length before base64 decode
CVE-2026-64125 9.8 CRITICAL net: bcmgenet: keep RBUF EEE/PM disabled
CVE-2026-64091 9.8 CRITICAL batman-adv: tt: fix TOCTOU race for reported vlans
CVE-2026-63808 9.8 CRITICAL exfat: fix potential use-after-free in exfat_find_dir_entry()
CVE-2026-63978 9.8 CRITICAL net/handshake: Drain pending requests at net namespace exit
CVE-2026-63979 9.8 CRITICAL net/handshake: hand off the pinned file reference to accept_doit
CVE-2026-64132 9.8 CRITICAL ipv6: ioam: refresh hdr pointer before ioam6_event()
CVE-2026-64136 9.8 CRITICAL smb: client: protect tc_count increment in smb2_find_smb_sess_tcon_unlocked()
CVE-2026-63800 9.8 CRITICAL pNFS: Fix use-after-free in pnfs_update_layout()

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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