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CVE-2026-93203 high CVSS 7.1

Vulnerability in Linux kernel (CVE-2026-93203)

Summary

Vulnerability in Linux kernel (CVE-2026-93203). 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:

batman-adv: bla: avoid CRC corruption due to parallel claim add

batadv_bla_add_claim() is used to add claims and modify the backbone of
claims for CLAIM frames from remote backbones and local packets. When it
handles a claim, it needs to either

  • add the new claim's CRC to the backbone CRC
  • remove the already existing claim's CRC from the old backbone and add it
    to the new backbone

But when the "new" claim code was running in parallel to the "change
backbone" code, it can happen that the CRC was invalid because the
backbone_gw of the claim was changed twice in the "new" claim code path:

  • CPU0 creates the claim for gateway A and publishes it in the claim
    hash. The crc16 of the address has not yet been added to A's crc at
    this point.

  • CPU1 processes a claim frame of gateway B for the same client, finds
    the just published claim, and performs the ownership change: it
    switches the pointer to B, removes the crc16 from A's crc - which
    never contained it - and adds it to B's crc.

  • CPU0 continues behind the creation branch, unconditionally switches
    the pointer back to A without compensating B's crc (its remove_crc
    is false for the creation path), and finally adds the crc16 to A's
    crc

The CRC is then wrong for both:

  • claim belongs to A: but CRC is not part of backbone A's CRC
  • claim doesn't belong to B: CRC is still part of backbone B's CRC

This wrong CRC is never recomputated from the…

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-2026-93203 has been found in Linux kernel.
Risk of unauthorized operations or information disclosure. CVSS score: 7.1/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-93203" on the vendor's site.

CVE-2026-93203 (Linux kernel) — CVSS v3 7.1
Attack vector: adjacent-network / 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

A vulnerability (unclassified) exists in Linux kernel.

📍 Affected scope

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

🔥 Severity

Severity: High (CVSS 7.1/10). 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。

References

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