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CVE-2026-31607 critical CVSS 9.8

Out-of-Bounds Write in Linux kernel (CVE-2026-31607)

Summary

Out-of-bounds write in Linux kernel (CVE-2026-31607). 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:

usbip: validate number_of_packets in usbip_pack_ret_submit()

When a USB/IP client receives a RET_SUBMIT response,
usbip_pack_ret_submit() unconditionally overwrites
urb->number_of_packets from the network PDU. This value is
subsequently used as the loop bound in usbip_recv_iso() and
usbip_pad_iso() to iterate over urb->iso_frame_desc[], a flexible
array whose size was fixed at URB allocation time based on the
original number_of_packets from the CMD_SUBMIT.

A malicious USB/IP server can set number_of_packets in the response
to a value larger than what was originally submitted, causing a heap
out-of-bounds write when usbip_recv_iso() writes to
urb->iso_frame_desc[i] beyond the allocated region.

KASAN confirmed this with kernel 7.0.0-rc5:

BUG: KASAN: slab-out-of-bounds in usbip_recv_iso+0x46a/0x640
Write of size 4 at addr ffff888106351d40 by task vhci_rx/69

The buggy address is located 0 bytes to the right of
allocated 320-byte region [ffff888106351c00, ffff888106351d40)

The server side (stub_rx.c) and gadget side (vudc_rx.c) already
validate number_of_packets in the CMD_SUBMIT path since commits
c6688ef9f297 ("usbip: fix stub_rx: harden CMD_SUBMIT path to handle
malicious input") and b78d830f0049 ("usbip: fix vudc_rx: harden
CMD_SUBMIT path to handle malicious input"). The server side validates
against USBIP_MAX_ISO_PACKETS because no URB exists yet at that point.
On the client side we have th…

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-2026-31607 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-2026-31607" on the vendor's site.

CVE-2026-31607 (Linux kernel) — CWE-787 / 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.

❓ What is the problem

Out-of-bounds write (CWE-787) exists in Linux kernel.

📍 Affected scope

Check the vendor advisory for the affected versions of Linux kernel.

🔥 Severity

Severity: Critical (CVSS 9.8/10). Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

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

  1. 1
    Identify 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。

  2. 2
    Post-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。

Affected packages

Linux Kernel
[{"type":"ECOSYSTEM","events":[{"introduced":"2.6.39"},{"fixed":"5.10.258"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.209"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.175"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.136"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.83"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.24"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.14"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.20.0"},{"fixed":"7.0.1"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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