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CVE-2026-31590— KVM: SEV: Drop WARN on large size for KVM_MEMORY_ENCRYPT_REG_REGION

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KVM SEV中sev_pin_memory()函数对npages溢出int类型未进行充分验证，用户空间可通过传递超大size值触发警告。

AI Predicted 7.5 Difficulty: Trivial EPSS 0.17% · P6

Affected Version Matrix 20

VendorProduct Version RangeStatus
Linux Linux 78824fabc72e5e37d51e6e567fde70a4fc41a6d7< 6a8e3c82122737529b25ef2a048fbcc569d8c055 affected
78824fabc72e5e37d51e6e567fde70a4fc41a6d7< a703933bcfa5cc76ca10e2048464600e74136099 affected
78824fabc72e5e37d51e6e567fde70a4fc41a6d7< abcd43ff579abd0a654bb4636086e78819dd5f4c affected
78824fabc72e5e37d51e6e567fde70a4fc41a6d7< b670833749ffd8681361db2bb047c6f2e3075f3a affected
78824fabc72e5e37d51e6e567fde70a4fc41a6d7< ab423e5892826202a660b5ac85d1125b0e8301a5 affected
78824fabc72e5e37d51e6e567fde70a4fc41a6d7< 28cc13ca20431b127d42d84ba10898d03e2c8267 affected
78824fabc72e5e37d51e6e567fde70a4fc41a6d7< c29ff288a2d97a6f4640a498a367cf0eb91312eb affected
78824fabc72e5e37d51e6e567fde70a4fc41a6d7< 1cba4dcd795daf6d257122779fb6a349edf03914 affected
… +12 more rows
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I. Basic Information for CVE-2026-31590

Vulnerability Information
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Vulnerability Title
KVM: SEV: Drop WARN on large size for KVM_MEMORY_ENCRYPT_REG_REGION
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Drop WARN on large size for KVM_MEMORY_ENCRYPT_REG_REGION Drop the WARN in sev_pin_memory() on npages overflowing an int, as the WARN is comically trivially to trigger from userspace, e.g. by doing: struct kvm_enc_region range = { .addr = 0, .size = -1ul, }; __vm_ioctl(vm, KVM_MEMORY_ENCRYPT_REG_REGION, &range); Note, the checks in sev_mem_enc_register_region() that presumably exist to verify the incoming address+size are completely worthless, as both "addr" and "size" are u64s and SEV is 64-bit only, i.e. they _can't_ be greater than ULONG_MAX. That wart will be cleaned up in the near future. if (range->addr > ULONG_MAX || range->size > ULONG_MAX) return -EINVAL; Opportunistically add a comment to explain why the code calculates the number of pages the "hard" way, e.g. instead of just shifting @ulen.
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KVM SEV中sev_pin_memory()函数对npages溢出int类型未进行充分验证，用户空间可通过传递超大size值触发警告。
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 78824fabc72e5e37d51e6e567fde70a4fc41a6d7 ~ 6a8e3c82122737529b25ef2a048fbcc569d8c055 -
Linux Linux 5.9 -

II. Public POCs for CVE-2026-31590

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III. Intelligence Information for CVE-2026-31590

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Patches & Fixes for CVE-2026-31590 (5)

Same Patch Batch · Linux · 2026-04-24 · 138 CVEs total

CVE-2026-31637 9.8 CRITICAL rxrpc: reject undecryptable rxkad response tickets
CVE-2026-31609 9.8 CRITICAL smb: client: avoid double-free in smbd_free_send_io() after smbd_send_batch_flush()
CVE-2026-31608 9.8 CRITICAL smb: server: avoid double-free in smb_direct_free_sendmsg after smb_direct_flush_send_list
CVE-2026-31633 9.8 CRITICAL rxrpc: Fix integer overflow in rxgk_verify_response()
CVE-2026-31657 9.8 CRITICAL batman-adv: hold claim backbone gateways by reference
CVE-2026-31669 9.8 CRITICAL mptcp: fix slab-use-after-free in __inet_lookup_established
CVE-2026-31668 9.8 CRITICAL seg6: separate dst_cache for input and output paths in seg6 lwtunnel
CVE-2026-31607 9.8 CRITICAL usbip: validate number_of_packets in usbip_pack_ret_submit()
CVE-2026-31536 9.8 CRITICAL smb: server: let send_done handle a completion without IB_SEND_SIGNALED
CVE-2026-31659 9.8 CRITICAL batman-adv: reject oversized global TT response buffers
CVE-2026-31649 9.8 CRITICAL net: stmmac: fix integer underflow in chain mode
CVE-2026-31589 9.8 CRITICAL mm: call ->free_folio() directly in folio_unmap_invalidate()
CVE-2026-31636 9.1 CRITICAL rxrpc: fix RESPONSE authenticator parser OOB read
CVE-2026-31570 8.8 HIGH can: gw: fix OOB heap access in cgw_csum_crc8_rel()
CVE-2026-31558 8.8 HIGH LoongArch: KVM: Make kvm_get_vcpu_by_cpuid() more robust
CVE-2026-31553 8.8 HIGH KVM: arm64: Fix the descriptor address in __kvm_at_swap_desc()
CVE-2026-31588 8.8 HIGH KVM: x86: Use scratch field in MMIO fragment to hold small write values
CVE-2026-31629 8.8 HIGH nfc: llcp: add missing return after LLCP_CLOSED checks
CVE-2026-31622 8.8 HIGH NFC: digital: Bounds check NFC-A cascade depth in SDD response handler
CVE-2026-31611 8.6 HIGH ksmbd: require 3 sub-authorities before reading sub_auth[2]

Showing top 20 of 138 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-31590

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