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CVE-2026-97563— smb: client: reject out-of-bounds DataOffset in CIFSSMBRead()

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.

在 Linux 内核中，已修复以下漏洞： smb: 客户端：拒绝 CIFSSMBRead() 中越界的 DataOffset SMB1 同步读取辅助函数 会验证服务器返回的 （数据长度）是否不超过 以及调用方提供的 ，但从未对 （数据偏移量）进行有效性检查。其拷贝源地址构建为： &pSMBr->hdr.Protocol + le16_to_cpu(pSMBr->DataOffset) 随后通过 复制 字节的数据，但并未检查 这一范围是否完全落在从服务器实际收到的响应缓冲区之内。 恶意或已被攻陷的 SMB1 服务器可

AI Predicted 5.5 Difficulty: Moderate EPSS 0.19% · P8

Affected Version Matrix 6

VendorProduct Version RangeStatus
Linux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 667feba13e78d16393aacb15869f70970f422227 affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 5be5bdda5863eacc964b609ba927764f253431b3 affected
2.6.12 affected
< 2.6.12 unaffected
7.2.7≤ 7.2.* unaffected
7.3-rc3≤ * unaffected
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I. Basic Information for CVE-2026-97563

Vulnerability Information
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Vulnerability Title
smb: client: reject out-of-bounds DataOffset in CIFSSMBRead()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: smb: client: reject out-of-bounds DataOffset in CIFSSMBRead() The SMB1 synchronous read helper CIFSSMBRead() validates the server's DataLength against CIFSMaxBufSize and the caller's count, but never validates DataOffset. The copy source is formed as &pSMBr->hdr.Protocol + le16_to_cpu(pSMBr->DataOffset) and memcpy()'d for DataLength bytes with no check that the [DataOffset, DataOffset + DataLength) range lies within the response actually received from the server. A malicious or compromised SMB1 server can return a response carrying an in-range DataLength and a large DataOffset, driving the source pointer past the end of the response buffer. The memcpy() then copies adjacent kernel heap into the caller's read buffer (information disclosure), or reads unmapped memory and oopses (denial of service). SMB1 is not negotiated by default; reaching this code requires an explicit vers=1.0 mount. Both DataOffset and the received response length recorded in rsp_iov.iov_len are relative to the start of the SMB header, so reject the response unless DataOffset + DataLength fits within that length, using overflow-safe arithmetic, before forming the source pointer. The response length has been validated by the previous patch, so the DataOffset and DataLength fields can be read safely here. While here, make data_length unsigned. It holds a length derived from unsigned on-the-wire fields and is only ever compared against unsigned quantities; print it with %u accordingly, and add __func__ to the cifs_dbg() calls in this function.
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

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 ~ 667feba13e78d16393aacb15869f70970f422227 -
Linux Linux 2.6.12 -

II. Public POCs for CVE-2026-97563

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III. Intelligence Information for CVE-2026-97563

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Patches & Fixes for CVE-2026-97563 (2)

Same Patch Batch · Linux · 2026-09-25 · 372 CVEs total

CVE-2026-100075 9.8 CRITICAL RDMA/srpt: Fix srpt_alloc_rw_ctxs() unwind counters
CVE-2026-97957 8.8 HIGH net: hinic: fix mailbox segment buffer overflow
CVE-2026-97527 8.8 HIGH scsi: qla2xxx: Serialize NVMe unsol ctx list with a per-fcport lock
CVE-2026-97528 8.8 HIGH scsi: qla2xxx: Unlink NVMe unsol ctx before freeing on LS reject error
CVE-2026-97555 8.8 HIGH smb: client: fix heap overflow in DACL owner/group rewrite
CVE-2026-98115 8.8 HIGH ksmbd: safely drain sessions during logoff
CVE-2026-97525 8.2 HIGH x86/mm/pat: Allocate split page tables as kernel page tables
CVE-2026-97573 8.1 HIGH bnxt_en: Handle buffer allocation failure in bnxt_rx_ring_reset()
CVE-2026-98070 8.1 HIGH net/rds: acquire RDS_IN_XMIT in rds_tcp_reset_callbacks()
CVE-2026-97570 8.1 HIGH bnxt_en: Bound SW TPA IDs to prevent crashes
CVE-2026-98069 8.1 HIGH net/rds: acquire the fastpath locks in rds_conn_shutdown()
CVE-2026-98130 8.1 HIGH sctp: fix a TOCTOU race in SCTP_CMD_TIMER_START
CVE-2026-98116 7.8 HIGH ALSA: pcm: Serialize PCM mmap with buffer reallocation to fix page UAF
CVE-2026-97903 7.8 HIGH exit: hold a reference to thread_pid across proc_flush_pid
CVE-2026-97548 7.8 HIGH xfs: fix the rtrmap and rtrefcount _maxlevels_ondisk functions
CVE-2026-97611 7.8 HIGH net: openvswitch: fix use-after-free of the flow table mask array
CVE-2026-97612 7.8 HIGH net: mpls: clear inner_protocol when the last label is popped
CVE-2026-98073 7.8 HIGH net: Remove conflicting altnames for dying netns in __dev_change_net_namespace().
CVE-2026-97602 7.8 HIGH inet: frags: invalidate queues before flushing them
CVE-2026-97577 7.8 HIGH media: verisilicon: rockchip: reject AV1 frames exceeding the tile capacity

Showing top 20 of 372 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-97563

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