Vulnerability in Elm Chan (CVE-2026-6686)
Summary
Vulnerability in Elm Chan (CVE-2026-6686). Confidential information can be exposed externally.
Original description
The description as published by the source.
FatFs R0.16 and earlier contains an uninitialized cluster exposure when f_lseek() extends files beyond EOF without zero-filling newly allocated clusters. This maps to CWE-908 (Use of Uninitialized Resource). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N (4.6, Medium). The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Partial.
Source: GitHub Security Advisories (Global) 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-2026-6686 has been found in Elm Chan.
Confidential information can be exposed externally. CVSS score: 4.6/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Elm Chan CVE-2026-6686" on the vendor's site.
CVE-2026-6686 (Elm Chan) — CWE-908 / CVSS v3 4.6
Attack vector: physical / 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.
A vulnerability (CWE-908) exists in Elm Chan.
Check the vendor advisory for the affected versions of Elm Chan.
Severity: Medium (CVSS 4.6/10). Confidential information can be exposed externally.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
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
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1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Elm Chan を使っているサービスとバージョンを洗い出す。
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2Post-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
- advisory runzero.com
- exploit github.com
- exploit runzero.com
- web nvd.nist.gov
- web elm-chan.org
- web runzero.com
- web runzero.com
- web github.com
- web elm-chan.org