CVE-2026-89722: Linux kernel · PCI/sysfs: Fix out-of-bounds read in pci_write_legacy_io()
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 26 Oct 2026, 17:16 UTC
Rated by Threat Radar · CVSS not yet scored by NVD
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Exploitation evidence
Disclosed: evidence found.
CVE published 11 Sep 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
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther 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 fix has been implemented in the Linux kernel to correctly handle the number of bytes read in pci_write_legacy_io(), preventing out-of-bounds reads. Users should apply the official kernel updates that include this fix. Since the legacy_io file is root-only and architecture-specific, limiting access to trusted administrators also mitigates risk.
Description
A vulnerability in the Linux kernel's PCI/sysfs interface caused out-of-bounds reads in the pci_write_legacy_io() function. This was due to unconditional 4-byte loads from a buffer that could be smaller, leading to slab-out-of-bounds reads reported by KASAN. The issue affected the legacy_io sysfs file, which is root-only and present only on Alpha and PowerPC architectures. The fix involved reading only the requested number of bytes using little-endian helpers to correctly handle byte ordering on different architectures.
References
- nvd.nist.gov/vuln/detail/CVE-2026-89722 (opens in a new tab)
- git.kernel.org/stable/c/7a99e9c7011905734cc2739038f2a224b6be0d1f (opens in a new tab)
- git.kernel.org/stable/c/dc76258d0132df1d831a5a29758bd448ca9c566e (opens in a new tab)
- git.kernel.org/stable/c/e892f05f1f790d5721cd8e3c561ed76da7e08bae (opens in a new tab)
- msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-89722.json (opens in a new tab)
- support.microsoft.com/lifecycle (opens in a new tab)
- first.org/cvss (opens in a new tab)
- ubuntu.com/security/CVE-2026-89722 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-89722 (opens in a new tab)
- git.kernel.org/linus/dc76258d0132df1d831a5a29758bd448ca9c566e (opens in a new tab)