Vulnerability in Mbed TLS (CVE-2026-25833)
Summary
Vulnerability in Mbed TLS (CVE-2026-25833). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 3.6.6 or later.
Original description
The description as published by the source.
Mbed TLS 3.5.0 to 3.6.5 fixed in 3.6.6 and 4.1.0 has a buffer overflow in the x509_inet_pton_ipv6() function
Source: NIST National Vulnerability Database NVD
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-2026-25833 has been found in Mbed TLS.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade Mbed TLS to 3.6.6 or later.
If unsure, ask your IT team or search "Mbed TLS CVE-2026-25833" on the vendor's site.
CVE-2026-25833 (Mbed TLS) — CWE-121 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 3.6.6 — apply immediately
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-121) exists in Mbed TLS.
Check the vendor advisory for the affected versions of Mbed TLS.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 3.6.6.
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 Mbed TLS 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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2Apply patch patch
Upgrade Mbed TLS to 3.6.6ステージング環境で 3.6.6 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
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3Post-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
- Alpine Linux ALPINE-CVE-2026-25833 mbedtls Fixed in: 3.6.6-r0
- Debian DEBIAN-CVE-2026-25833 mbedtls
- Ubuntu UBUNTU-CVE-2026-25833 mbedtls
References
- patch cve@mitre.org
- patch cve@mitre.org