Vulnerability in Linux kernel (CVE-2026-89722)
Summary
Vulnerability in Linux kernel (CVE-2026-89722). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
PCI/sysfs: Fix out-of-bounds read in pci_write_legacy_io()
pci_write_legacy_io() loads 4 bytes from the kernfs write buffer
regardless of how many bytes userspace wrote:
if (count != 1 && count != 2 && count != 4)
return -EINVAL;
return pci_legacy_write(bus, off, *(u32 *)buf, count);
kernfs_fop_write_iter() allocates the buffer with kmalloc(len + 1),
so a 1-byte write to the legacy_io sysfs file allocates 2 bytes and
the unconditional u32 load reads up to 2 bytes past the end of the
allocation, which KASAN reports as a slab-out-of-bounds read.
Similarly, a 2-byte write overreads by 1 byte.
Thus, read only the number of bytes requested using get_unaligned_le16()
and get_unaligned_le32() for the 2 and 4 byte cases, interpreting the
buffer as little-endian to match the byte ordering of PCI I/O port
space.
The PowerPC implementation previously compensated for the generic
code's native-endian 32-bit load by shifting the value into place
for the 1 and 2 byte cases. The shifts were only correct on
big-endian kernels.
On little-endian PowerPC (POWER8 and later), they extracted the wrong
bytes, so a 1-byte write wrote an out-of-bounds byte instead of the
requested value. On big-endian, the native load also caused out_le16()
and out_le32() to reverse the user's bytes on the wire for 2 and 4 byte
writes. The little-endian helpers resolve both issues, so the shifts
are removed.
No changes are ne…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-89722 has been found in Linux kernel.
Risk of unauthorized operations or information disclosure.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-89722" on the vendor's site.
CVE-2026-89722 (Linux kernel)
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (unclassified) exists in Linux kernel.
Check the vendor advisory for the affected versions of Linux kernel.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Linux kernel を使っているサービスとバージョンを洗い出す。
-
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-89722 linux
- Ubuntu UBUNTU-CVE-2026-89722 linux
References
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web nvd.nist.gov
- web github.com