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CVE-2026-98127

Vulnerability in Linux kernel (CVE-2026-98127)

Summary

Vulnerability in Linux kernel (CVE-2026-98127). 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:

smb/client: validate new EOF for insert range

smb3_insert_range() does not check if the new file size
(i_size + len) is valid. This allows FALLOC_FL_INSERT_RANGE to bypass
RLIMIT_FSIZE, exceed s_maxbytes, or produce a size outside the loff_t
range.

Use check_add_overflow() to calculate the new EOF. Validate it with
inode_newsize_ok() before modifying the file.

Reproducer, using a file on a CIFS mount:

bash -c '
	FILE=/mnt/cifs/repro

	trap "" SIGXFSZ
	ulimit -f 3072		# RLIMIT_FSIZE = 3 MiB

	# A regular write is stopped at 3 MiB.
	dd if=/dev/zero of="$FILE" bs=1M count=4 status=none
	stat -c "size after write: %s" "$FILE"

	# Insert 2 MiB into a 2 MiB file.
	truncate -s 2M "$FILE"
	fallocate -i -o 0 -l 2M "$FILE"
	stat -c "size after insert: %s" "$FILE"
'

Before this change, the regular write stops at the 3 MiB limit, but
insert range grows the file to 4 MiB:

dd: error writing '/mnt/cifs/repro': File too large
size after write: 3145728
size after insert: 4194304

After this change, insert range also fails at the limit and leaves the
2 MiB file unchanged:

dd: error writing '/mnt/cifs/repro': File too large
size after write: 3145728
fallocate: fallocate failed: File too large
size after insert: 2097152

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-2026-98127 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-2026-98127" on the vendor's site.

CVE-2026-98127 (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.

❓ What is the problem

A vulnerability (unclassified) exists in Linux kernel.

📍 Affected scope

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

🔥 Severity

Severity: ?. Risk of unauthorized operations or information disclosure.

🔧 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":"5.13.0"},{"fixed":"6.12.111"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.53"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.7"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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