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CVE-2026-64289— iommufd: Set upper bounds on cache invalidation entry_num and entry_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基金会开源的一款操作系统内核。 Linux kernel 6.8版本存在安全漏洞，该漏洞源于iommufd_hwpt_invalidate()函数对用户控制的entry_num和entry_len未设置合理上限，可能导致软锁定或CPU挂起，造成拒绝服务。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.16% · P5

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux 8c6eabae3807e048b9f17733af5e20500fbf858c< d2bd041e0efaf7d81789779b135279d18b33d6d5 affected
8c6eabae3807e048b9f17733af5e20500fbf858c< 32ca4aed2a66205b072fcfecabe220289a8149ff affected
8c6eabae3807e048b9f17733af5e20500fbf858c< 2c6381d90898089287e0a358f06f89f6b4b389f2 affected
8c6eabae3807e048b9f17733af5e20500fbf858c< 4d70986002f2f3eaaed89124fb2522bded38b016 affected
6.8 affected
< 6.8 unaffected
6.12.96≤ 6.12.* unaffected
6.18.39≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-64289

Vulnerability Information
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Vulnerability Title
iommufd: Set upper bounds on cache invalidation entry_num and entry_len
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: iommufd: Set upper bounds on cache invalidation entry_num and entry_len iommufd_hwpt_invalidate() takes a user-controlled entry_num and entry_len, each bounded only by U32_MAX. An entry_len beyond the kernel's struct size makes the copy helper verify the extra bytes are zero, scanning that excess in one uninterruptible pass; a multi-gigabyte value over zeroed user memory trips the soft-lockup watchdog. A large entry_num is the other half, driving the backend invalidation loop with no reschedule. The VT-d nested handler, for one, copies each entry and flushes caches per iteration, pinning the CPU on a non-preemptible kernel. Cap both in the ioctl. entry_len is held under PAGE_SIZE, above any request struct, and entry_num under 1 << 19, the order of a hardware invalidation queue and well beyond any real batch, bounding the per-call loop length.
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 6.8版本存在安全漏洞，该漏洞源于iommufd_hwpt_invalidate()函数对用户控制的entry_num和entry_len未设置合理上限，可能导致软锁定或CPU挂起，造成拒绝服务。
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 8c6eabae3807e048b9f17733af5e20500fbf858c ~ d2bd041e0efaf7d81789779b135279d18b33d6d5 -
Linux Linux 6.8 -

II. Public POCs for CVE-2026-64289

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III. Intelligence Information for CVE-2026-64289

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Patches & Fixes for CVE-2026-64289 (4)

Same Patch Batch · Linux · 2026-07-25 · 274 CVEs total

CVE-2026-64355 9.8 CRITICAL bpf: Reject fragmented frames in devmap
CVE-2026-64459 9.8 CRITICAL tcp: restore RCU grace period in tcp_ao_destroy_sock
CVE-2026-64303 9.8 CRITICAL spi: fsl-lpspi: terminate the RX channel on TX prepare failure path
CVE-2026-64439 9.8 CRITICAL crypto: krb5 - filter out async aead implementations at alloc
CVE-2026-64410 9.8 CRITICAL netfilter: flowtable: IPIP tunnel hardware offload is not yet support
CVE-2026-64399 9.8 CRITICAL ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE
CVE-2026-64397 9.8 CRITICAL ksmbd: serialize QUERY_DIRECTORY requests per file
CVE-2026-64391 9.8 CRITICAL ksmbd: use opener credentials for ADS I/O
CVE-2026-64387 9.8 CRITICAL smb: client: fix query directory replay double-free
CVE-2026-64386 9.8 CRITICAL smb: client: fix query_info() replay double-free
CVE-2026-64385 9.8 CRITICAL smb: client: fix double-free in SMB2_ioctl() replay
CVE-2026-64383 9.8 CRITICAL smb: client: fix double-free in SMB2_flush() replay
CVE-2026-64384 9.8 CRITICAL smb: client: fix change notify replay double-free
CVE-2026-64268 9.8 CRITICAL RDMA/siw: bound Read Response placement to the RREAD length
CVE-2026-64523 9.8 CRITICAL net/handshake: Take a long-lived file reference at submit
CVE-2026-64257 9.1 CRITICAL smb: client: reject overlapping data areas in SMB2 responses
CVE-2026-64392 9.1 CRITICAL ksmbd: use opener credentials for delete-on-close
CVE-2026-64393 9.1 CRITICAL ksmbd: run set info with opener credentials
CVE-2026-64269 9.1 CRITICAL RDMA/rtrs-srv: Bound RDMA-Write length to chunk size in rdma_write_sg
CVE-2026-64319 9.1 CRITICAL nvmet-auth: validate reply message payload bounds against transfer length

Showing top 20 of 274 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-64289

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