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CVE-2026-63996— ethtool: cmis: require exact CDB reply length

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 6.11版本存在安全漏洞，该漏洞源于恶意SFP模块可能返回超出预期长度的CDB回复，导致越界写入。

CVSS 7.8 · High EPSS 0.13% · P2

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux a39c84d796254e6b1662ca0c46dbc313379e9291< 2f818cc98fd2c63a08239cb48995f6c3bfe9d9b3 affected
a39c84d796254e6b1662ca0c46dbc313379e9291< 4d42fb88ec61f2e98c33a9e3a2de371d5edbc6b1 affected
a39c84d796254e6b1662ca0c46dbc313379e9291< eb5dcd740cd7fa27bc2caeff2d28ef28e93ff4d3 affected
a39c84d796254e6b1662ca0c46dbc313379e9291< 6c3f999a9d1338c6c89a9ff4549eafe72bc2e7b1 affected
6.11 affected
< 6.11 unaffected
6.12.93≤ 6.12.* unaffected
6.18.35≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-63996

Vulnerability Information
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Vulnerability Title
ethtool: cmis: require exact CDB reply length
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ethtool: cmis: require exact CDB reply length Malicious SFP module could respond with rpl_len longer than what cmis_cdb_process_reply() expected, leading to OOB writes. Malicious HW is a bit theoretical but some modules may just be buggy and/or the reads may occasionally get corrupted, so let's protect the kernel. The existing check protects from short replies. We need to protect from long ones, too. All callers that pass a non-zero rpl_exp_len cast the reply payload to a fixed-layout struct and read fields at fixed offsets, with no version negotiation or short-reply handling: - cmis_cdb_validate_password() - cmis_cdb_module_features_get() - cmis_fw_update_fw_mng_features_get() so let's assume that responses longer than expected do not have to be handled gracefully here. Add a warning message to make the debug easier in case my understanding is wrong... Note that page_data->length (argument of kmalloc) comes from last arg to ethtool_cmis_page_init() which is rpl_exp_len. Note2 that AIs also like to point out overflows in args->req.payload itself (which is a fixed-size 120 B buffer, on the stack), but callers should be reading structs defined by the standard, so protecting from requests for more data than max seem like defensive programming.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/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基金会开源的一款操作系统内核。 Linux kernel 6.11版本存在安全漏洞，该漏洞源于恶意SFP模块可能返回超出预期长度的CDB回复，导致越界写入。
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 a39c84d796254e6b1662ca0c46dbc313379e9291 ~ 2f818cc98fd2c63a08239cb48995f6c3bfe9d9b3 -
Linux Linux 6.11 -

II. Public POCs for CVE-2026-63996

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III. Intelligence Information for CVE-2026-63996

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Patches & Fixes for CVE-2026-63996 (3)

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-2026-64068 9.8 CRITICAL netfs: Fix missing locking around retry adding new subreqs
CVE-2026-63993 9.8 CRITICAL vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()
CVE-2026-64142 9.8 CRITICAL ksmbd: close durable scavenger races against m_fp_list lookups
CVE-2026-64033 9.8 CRITICAL RDMA/rtrs: Fix use-after-free in path file creation cleanup
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-2026-64061 9.8 CRITICAL netfs: Fix early put of sink folio in netfs_read_gaps()
CVE-2026-64025 9.8 CRITICAL bpf, skmsg: fix verdict sk_data_ready racing with ktls rx
CVE-2026-64089 9.8 CRITICAL batman-adv: tt: fix negative last_changeset_len
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-2026-64066 9.8 CRITICAL netfs: Fix netfs_read_to_pagecache() to pause on subreq failure
CVE-2026-63887 9.8 CRITICAL scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf
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-2026-64132 9.8 CRITICAL ipv6: ioam: refresh hdr pointer before ioam6_event()
CVE-2026-63979 9.8 CRITICAL net/handshake: hand off the pinned file reference to accept_doit
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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