CVE-2026-31590: Linux kernel · KVM: SEV: Drop WARN on large size for KVM_MEMORY_ENCRYPT_REG_REGION
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in c29ff288a2d97a6f4640a498a367cf0eb91312eb : update Linux kernel when convenient.
Data as of 6 Nov 2026, 16:04 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
Thin evidence
One scorer or none- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-11-06.
- Patch
- Available – fixed in c29ff288a2d97a6f4640a498a367cf0eb91312eb, b670833749ffd8681361db2bb047c6f2e3075f3a, abcd43ff579abd0a654bb4636086e78819dd5f4c +6
Exploitation evidence
Disclosed: evidence found.
CVE published 24 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
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.
References
- git.kernel.org/stable/c/6a8e3c82122737529b25ef2a048fbcc569d8c055 (opens in a new tab)
- git.kernel.org/stable/c/a703933bcfa5cc76ca10e2048464600e74136099 (opens in a new tab)
- git.kernel.org/stable/c/abcd43ff579abd0a654bb4636086e78819dd5f4c (opens in a new tab)
- git.kernel.org/stable/c/b670833749ffd8681361db2bb047c6f2e3075f3a (opens in a new tab)
- git.kernel.org/stable/c/ab423e5892826202a660b5ac85d1125b0e8301a5 (opens in a new tab)
- git.kernel.org/stable/c/28cc13ca20431b127d42d84ba10898d03e2c8267 (opens in a new tab)
- git.kernel.org/stable/c/c29ff288a2d97a6f4640a498a367cf0eb91312eb (opens in a new tab)
- git.kernel.org/stable/c/1cba4dcd795daf6d257122779fb6a349edf03914 (opens in a new tab)
- git.kernel.org/stable/c/8acffeef5ef720c35e513e322ab08e32683f32f2 (opens in a new tab)