Vulnerability in Linux kernel (CVE-2026-89702)
Summary
Vulnerability in Linux kernel (CVE-2026-89702). Successful exploitation can lead to full system takeover.
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
nfsd: size fh_verify server sockaddr slot by xpt_locallen
The nfsd_fh_verify and nfsd_fh_verify_err tracepoints declare the
server sockaddr slot sized by xpt_remotelen but fill it from
xpt_local using xpt_locallen:
TP_STRUCT__entry(
...
__sockaddr(server, rqstp->rq_xprt->xpt_remotelen)
...
)
TP_fast_assign(
...
__assign_sockaddr(server, &rqstp->rq_xprt->xpt_local,
rqstp->rq_xprt->xpt_locallen);
...
)
When xpt_locallen exceeds xpt_remotelen, __assign_sockaddr's memcpy
writes past the reserved ring-buffer slot. In the reverse direction
(xpt_locallen < xpt_remotelen) the slot is oversized and the
unwritten tail leaks prior ring-buffer contents to trace consumers.
The write-past-end case is reachable on NFS/UDP. svc_xprt_set_remote()
is only called from svc_tcp_accept() (net/sunrpc/svcsock.c) and from
the RDMA connect path; svc_create_socket() for UDP calls only
svc_xprt_set_local(), so xpt_remotelen stays 0 for the xprt's
lifetime. Every fh_verify trace for an NFSv2/v3-over-UDP request
then copies 16 or 28 bytes from xpt_local into a zero-byte slot.
The other NFSD tracepoints that record the server address
(NFSD_TRACE_PROC_CALL_FIELDS, NFSD_TRACE_PROC_RES_FIELDS,
SVC_RQST_ENDPOINT_FIELDS) already size the server slot by
xpt_locallen; nfsd_fh_verify and nfsd_fh_verify_err were the only
excep…
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-2026-89702 has been found in Linux kernel.
Successful exploitation can lead to full system takeover. CVSS score: 9.8/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-89702" on the vendor's site.
CVE-2026-89702 (Linux kernel) — CVSS v3 9.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
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: Critical (CVSS 9.8/10). Successful exploitation can lead to full system takeover.
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
- Ubuntu UBUNTU-CVE-2026-89702 linux-hwe-edge
References
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web nvd.nist.gov
- web github.com