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CVE-2026-42767 medium CVSS 5.9

Vulnerability in Openssl (CVE-2026-42767)

Summary

Vulnerability in Openssl (CVE-2026-42767). Risk of unauthorized operations or information disclosure.

Original description

The description as published by the source.

Issue summary: An attacker-controlled CMP (Certificate Management Protocol)
server could trigger a NULL pointer dereference in a CMP client application.

Impact summary: A NULL pointer dereference causes a crash of the
application and a Denial of Service.

An attacker controlling a CMP server (or acting as a man-in-the-middle) could
craft a CMP response containing a CRMF (Certificate Request Message Format)
CertRepMessage with an EncryptedValue structure where the symmAlg field
has an algorithm OID but no parameters field. When the OpenSSL CMP client
processes this response, the NULL dereference occurs, causing a crash of
the CMP client.

Applications that process untrusted CMP/CRMF messages may be affected.

The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this
issue, as the affected code is outside the OpenSSL FIPS module boundary.

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-2026-42767 has been found in Openssl.
Risk of unauthorized operations or information disclosure. CVSS score: 5.9/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Openssl CVE-2026-42767" on the vendor's site.

CVE-2026-42767 (Openssl) — CWE-476 / CVSS v3 5.9
Attack vector: remote (network-reachable) / 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 (CWE-476) exists in Openssl.

📍 Affected scope

Check the vendor advisory for the affected versions of Openssl.

🔥 Severity

Severity: Medium (CVSS 5.9/10). 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. Run grep -r 'Openssl' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'Openssl' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で Openssl を grep し、稼働しているサービス・バージョンを把握する。

  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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