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CVE-2026-31478— ksmbd: replace hardcoded hdr2_len with offsetof() in smb2_calc_max_out_buf_len()

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基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于使用硬编码的hdr2_len值，可能导致响应缓冲区管理错误。

CVSS 9.8 · Critical EPSS 0.74% · P53

Possible ATT&CK Techniques 1 AI

T1564.004 · NTFS File Attributes

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux f2283680a80571ca82d710bc6ecd8f8beac67d63< 70b4c414889492c522b6e4331562360f49be2361 affected
9f297df20d93411c0b4ddad7f88ba04a7cd36e77< 9a7166f0ef8cbb7bb48dd05e2471d995566003f5 affected
e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d< c3a89e3ec1ccf64fa6a34e391e1581ebbcba8683 affected
e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d< 6aef1765d6807e0f027cd87f6ac973eb0879a46d affected
e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d< 80824c7e527b70cf9039534e60aff592e8f209d1 affected
e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d< 4cb537ae4f37d7d0f617815ed4bed7173fb50861 affected
e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d< 0e55f63dd08f09651d39e1b709a91705a8a0ddcb affected
5.15.145< 5.15.203 affected
… +10 more rows
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I. Basic Information for CVE-2026-31478

Vulnerability Information
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Vulnerability Title
ksmbd: replace hardcoded hdr2_len with offsetof() in smb2_calc_max_out_buf_len()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: replace hardcoded hdr2_len with offsetof() in smb2_calc_max_out_buf_len() After this commit (e2b76ab8b5c9 "ksmbd: add support for read compound"), response buffer management was changed to use dynamic iov array. In the new design, smb2_calc_max_out_buf_len() expects the second argument (hdr2_len) to be the offset of ->Buffer field in the response structure, not a hardcoded magic number. Fix the remaining call sites to use the correct offsetof() value.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于使用硬编码的hdr2_len值，可能导致响应缓冲区管理错误。
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)

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Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux f2283680a80571ca82d710bc6ecd8f8beac67d63 ~ 70b4c414889492c522b6e4331562360f49be2361 -
Linux Linux 6.6 -

II. Public POCs for CVE-2026-31478

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III. Intelligence Information for CVE-2026-31478

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Same Patch Batch · Linux · 2026-04-22 · 100 CVEs total

CVE-2026-31463 9.8 CRITICAL iomap: fix invalid folio access when i_blkbits differs from I/O granularity
CVE-2026-31501 9.8 CRITICAL net: ti: icssg-prueth: fix use-after-free of CPPI descriptor in RX path
CVE-2026-31436 9.8 CRITICAL dmaengine: idxd: fix possible wrong descriptor completion in llist_abort_desc()
CVE-2026-31444 9.8 CRITICAL ksmbd: fix use-after-free and NULL deref in smb_grant_oplock()
CVE-2026-31448 9.4 CRITICAL ext4: avoid infinite loops caused by residual data
CVE-2026-31450 8.8 HIGH ext4: publish jinode after initialization
CVE-2026-31433 8.8 HIGH ksmbd: fix potencial OOB in get_file_all_info() for compound requests
CVE-2026-31435 8.8 HIGH netfs: Fix read abandonment during retry
CVE-2026-31432 8.8 HIGH ksmbd: fix OOB write in QUERY_INFO for compound requests
CVE-2026-31476 8.2 HIGH ksmbd: do not expire session on binding failure
CVE-2026-31513 8.1 HIGH Bluetooth: L2CAP: Fix stack-out-of-bounds read in l2cap_ecred_conn_req
CVE-2026-31464 8.1 HIGH scsi: ibmvfc: Fix OOB access in ibmvfc_discover_targets_done()
CVE-2026-31449 7.8 HIGH ext4: validate p_idx bounds in ext4_ext_correct_indexes
CVE-2026-31454 7.8 HIGH xfs: save ailp before dropping the AIL lock in push callbacks
CVE-2026-31453 7.8 HIGH xfs: avoid dereferencing log items after push callbacks
CVE-2026-31471 7.8 HIGH xfrm: iptfs: only publish mode_data after clone setup
CVE-2026-31502 7.8 HIGH team: fix header_ops type confusion with non-Ethernet ports
CVE-2026-31468 7.8 HIGH vfio/pci: Fix double free in dma-buf feature
CVE-2026-31494 7.8 HIGH net: macb: use the current queue number for stats
CVE-2026-31469 7.8 HIGH virtio_net: Fix UAF on dst_ops when IFF_XMIT_DST_RELEASE is cleared and napi_tx is false

Showing top 20 of 100 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-31478

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