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CVE-2026-43188 medium CVSS 5.5

Vulnerability in Linux kernel (CVE-2026-43188)

Summary

Vulnerability in Linux kernel (CVE-2026-43188). Risk of unauthorized operations or information disclosure. Exploitable via ceph_wbc.pages.

Original description

The description as published by the source.

In the Linux kernel, the following vulnerability has been resolved:

ceph: do not propagate page array emplacement errors as batch errors

When fscrypt is enabled, move_dirty_folio_in_page_array() may fail
because it needs to allocate bounce buffers to store the encrypted
versions of each folio. Each folio beyond the first allocates its bounce
buffer with GFP_NOWAIT. Failures are common (and expected) under this
allocation mode; they should flush (not abort) the batch.

However, ceph_process_folio_batch() uses the same rc variable for its
own return code and for capturing the return codes of its routine calls;
failing to reset rc back to 0 results in the error being propagated
out to the main writeback loop, which cannot actually tolerate any
errors here: once ceph_wbc.pages is allocated, it must be passed to
ceph_submit_write() to be freed. If it survives until the next iteration
(e.g. due to the goto being followed), ceph_allocate_page_array()'s
BUG_ON() will oops the worker.

Note that this failure mode is currently masked due to another bug
(addressed next in this series) that prevents multiple encrypted folios
from being selected for the same write.

For now, just reset rc when redirtying the folio to prevent errors in
move_dirty_folio_in_page_array() from propagating. Note that
move_dirty_folio_in_page_array() is careful never to return errors on
the first folio, so there is no need to check for that. After this
change, ceph_process_folio_batch() no longer retur…

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-2026-43188 has been found in Linux kernel.
Attackers can target a specific entry point like ceph_wbc.pages over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.5/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-43188" on the vendor's site.

CVE-2026-43188 (Linux kernel) — CVSS v3 5.5
Attack vector: local / no user interaction
Attack surface: ceph_wbc.pages
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. Attackers reach the vulnerable code path via ceph_wbc.pages.

📍 Affected scope

Check the vendor advisory for the affected versions of Linux kernel. Attack surface: ceph_wbc.pages.

🔥 Severity

Severity: Medium (CVSS 5.5/10). 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":"6.15.0"},{"fixed":"6.18.16"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.6"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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