Categories
CVE-2025-39691 high CVSS 7.8

Use-After-Free in Linux kernel (CVE-2025-39691)

Summary

Vulnerability in Linux kernel (CVE-2025-39691). 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:

fs/buffer: fix use-after-free when call bh_read() helper

There's issue as follows:
BUG: KASAN: stack-out-of-bounds in end_buffer_read_sync+0xe3/0x110
Read of size 8 at addr ffffc9000168f7f8 by task swapper/3/0
CPU: 3 UID: 0 PID: 0 Comm: swapper/3 Not tainted 6.16.0-862.14.0.6.x86_64
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
Call Trace:

dump_stack_lvl+0x55/0x70
print_address_description.constprop.0+0x2c/0x390
print_report+0xb4/0x270
kasan_report+0xb8/0xf0
end_buffer_read_sync+0xe3/0x110
end_bio_bh_io_sync+0x56/0x80
blk_update_request+0x30a/0x720
scsi_end_request+0x51/0x2b0
scsi_io_completion+0xe3/0x480
? scsi_device_unbusy+0x11e/0x160
blk_complete_reqs+0x7b/0x90
handle_softirqs+0xef/0x370
irq_exit_rcu+0xa5/0xd0
sysvec_apic_timer_interrupt+0x6e/0x90

Above issue happens when do ntfs3 filesystem mount, issue may happens
as follows:
mount IRQ
ntfs_fill_super
read_cache_page
do_read_cache_folio
filemap_read_folio
mpage_read_folio
do_mpage_readpage
ntfs_get_block_vbo
bh_read
submit_bh
wait_on_buffer(bh);
blk_complete_reqs
scsi_io_completion
scsi_end_request
blk_update_request
end_bio_bh_io_sync
end_buffer_read_sync
__end_buffer_read_notouch
unlock_buffer

        wait_on_buffer(bh);--> return will return to ca…

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-2025-39691 has been found in Linux kernel.
Successful exploitation can lead to full system takeover. CVSS score: 7.8/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2025-39691" on the vendor's site.

CVE-2025-39691 (Linux kernel) — CWE-416 / CVSS v3 7.8
Attack vector: local / 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

Use-after-free (CWE-416) exists in Linux kernel.

📍 Affected scope

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

🔥 Severity

Severity: High (CVSS 7.8/10). 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。

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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