CVE-2026-23005: Linux kernel · x86/fpu: Clear XSTATE_BV[i] in guest XSAVE state whenever XFD[i]=1
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 High · fixed in 6.8.0-1057.60~22.04.1 : patch Linux kernel soon.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 12% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 6.8.0-1057.60~22.04.1, 6.8.0-1059.65~22.04.1, 6.8.0-1058.65~22.04.1 +37
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 25 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linuxpkg:deb/ubuntu/linux?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A patch is available and should be applied to affected Linux kernel versions to resolve this issue. The fix ensures that XSTATE_BV bits corresponding to disabled features in the guest's XFD are cleared before loading XSAVE state, preventing kernel panics. Users should update to the fixed kernel versions as provided by their distribution or vendor. No additional mitigation is required beyond applying the official fix.
Description
A vulnerability in the Linux kernel's x86/fpu subsystem related to handling guest XSAVE state in KVM was resolved. The issue involved improper clearing of XSTATE_BV bits when features were disabled via the guest's XFD, causing kernel panics due to XRSTOR faults. This could occur during guest WRMSR operations or when loading guest XSAVE state, leading to kernel crashes. The fix ensures that disabled features are cleared from the saved state to prevent such faults. This vulnerability affects specific Linux kernel versions and has a medium severity rating.
References
- ubuntu.com/security/CVE-2026-23005 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-23005 (opens in a new tab)
- git.kernel.org/linus/b45f721775947a84996deb5c661602254ce25ce6 (opens in a new tab)
- git.kernel.org/stable/c/b45f721775947a84996deb5c661602254ce25ce6 (opens in a new tab)
- git.kernel.org/stable/c/eea6f395ca502c4528314c8112da9b5d65f685eb (opens in a new tab)
- git.kernel.org/stable/c/f577508cc8a0adb8b4ebe9480bba7683b6149930 (opens in a new tab)
- ubuntu.com/security/notices/USN-8278-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8289-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8296-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8296-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8289-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8278-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8393-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8440-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8499-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8570-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8594-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8604-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8605-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8570-2 (opens in a new tab)