Common Problems

Common Problems 112473

Windows Server 2019 — DHCP NACK storms after VLAN resegmentation create widespread endpoint disconnects — Fix & Prevention

🟡 Medium   ⏱ 5–30 min  Last verified: 17 September 2020 Affected versions: Windows Server 2019 📖 ~2 min read Table of contents Symptom & Impact Environment & Reproduction Root Cause Analysis Quick Triage Step-by-Step Diagnosis Solution — Primary Fix Solution — Alternative Approaches Verification & Acceptance Criteria Rollback Plan Prevention & Hardening Related Errors […]

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Ubuntu 18.04 — postsrsd — vulnerability — patch and remediation guide — diagnosis and fix on Ubuntu 18.04

Ubuntu 18.04 — postsrsd — vulnerability — patch and remediation guide

🟢 Low   ⏱ 5–15 min  Last verified: 17 September 2020 Affected versions: Ubuntu 18.04 (bionic) 📖 ~4 min read  •  Source: Ubuntu Security Notice USN-4730-1 Related CVEs: CVE-2020-35573 Upstream summary: It was discovered that PostSRSd mishandled certain input. A remote attacker could use this vulnerability to cause a denial of service via a long […]

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Gentoo Linux — net-analyzer/ossec-hids — multiple vulnerabilities (7 CVEs) — patch and remediation guide — diagnosis and fix on Gentoo Linux

Gentoo Linux — net-analyzer/ossec-hids — multiple vulnerabilities (7 CVEs) — patch and remediation guide

🟠 High   ⏱ 15–60 min  Last verified: 25 May 2026 Affected versions: Gentoo Linux 📖 ~4 min read  •  Source: Gentoo GLSA GLSA-202007-33 Related CVEs: CVE-2020-8442 CVE-2020-8443 CVE-2020-8444 CVE-2020-8445 CVE-2020-8446 CVE-2020-8447 CVE-2020-8448 Upstream summary: Multiple vulnerabilities have been discovered in OSSEC. Please review the CVE identifiers referenced below for details. Table of contents Symptom […]

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Oracle Linux 8 — libpcap security, bug fix, and — enhancement update — new behaviour and fixes — diagnosis and fix on Oracle Linux 8

Oracle Linux 8 — libpcap security, bug fix, and — enhancement update — new behaviour and fixes (ELSA-2020-4547)

🟢 Low   ⏱ 5–15 min  Last verified: 16 September 2020 Affected versions: Oracle Linux 8 📖 ~4 min read  •  Source: ELSA advisory ELSA-2020-4547 Related CVEs: CVE-2019-15165 Table of contents Symptom & Impact Environment & Reproduction Root Cause Analysis Quick Triage Step-by-Step Diagnosis Solution – Primary Fix Solution – Alternative Approaches Verification & Acceptance […]

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Common Problems 118125

Ubuntu 18.04 LTS – Certbot renewal fails because port 80 is in use – Fix & Prevention

🟡 Medium   ⏱ 5–30 min  Last verified: 16 September 2020 Affected versions: Ubuntu 18.04 LTS 📖 ~1 min read Table of contents Symptom & Impact Environment & Reproduction Root Cause Analysis Quick Triage Step-by-Step Diagnosis Solution – Primary Fix Solution – Alternative Approaches Verification & Acceptance Criteria Rollback Plan Prevention & Hardening Related Errors […]

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Ubuntu 16.04 — slirp — multiple vulnerabilities (2 CVEs) — patch and remediation guide — diagnosis and fix on Ubuntu 16.04

Ubuntu 16.04 — slirp — multiple vulnerabilities (2 CVEs) — patch and remediation guide

🟢 Low   ⏱ 5–15 min  Last verified: 16 September 2020 Affected versions: Ubuntu 16.04 (xenial) 📖 ~4 min read  •  Source: Ubuntu Security Notice USN-4632-1 Related CVEs: CVE-2020-7039 CVE-2020-8608 Upstream summary: It was discovered that the SLiRP networking implementation of the QEMU emulator did not properly manage memory under certain circumstances. An attacker could […]

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Oracle Linux 8 — binutils — vulnerability — patch and remediation guide — diagnosis and fix on Oracle Linux 8

Oracle Linux 8 — binutils — vulnerability — patch and remediation guide (ELSA-2024-9689)

🟢 Low   ⏱ 5–15 min  Last verified: 16 September 2020 Affected versions: Oracle Linux 8 📖 ~4 min read  •  Source: ELSA advisory ELSA-2024-9689 Related CVEs: CVE-2018-12699 Table of contents Symptom & Impact Environment & Reproduction Root Cause Analysis Quick Triage Step-by-Step Diagnosis Solution – Primary Fix Solution – Alternative Approaches Verification & Acceptance […]

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Oracle Linux 8 — perl-CPAN — vulnerability — patch and remediation guide — diagnosis and fix on Oracle Linux 8

Oracle Linux 8 — perl-CPAN — vulnerability — patch and remediation guide (ELSA-2025-8432)

🟡 Medium   ⏱ 10–30 min  Last verified: 16 September 2020 Affected versions: Oracle Linux 8 📖 ~4 min read  •  Source: ELSA advisory ELSA-2025-8432 Related CVEs: CVE-2020-16156 Table of contents Symptom & Impact Environment & Reproduction Root Cause Analysis Quick Triage Step-by-Step Diagnosis Solution – Primary Fix Solution – Alternative Approaches Verification & Acceptance […]

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Oracle Linux 8 — pki-core:10.6 and pki-deps:10.6 security, bug fix, and — enhancement update — new behaviour and fixes — diagnosis and fix on Oracle Linux 8

Oracle Linux 8 — pki-core:10.6 and pki-deps:10.6 security, bug fix, and — enhancement update — new behaviour and fixes (ELSA-2020-1644)

🟡 Medium   ⏱ 10–30 min  Last verified: 15 September 2020 Affected versions: Oracle Linux 8 📖 ~4 min read  •  Source: ELSA advisory ELSA-2020-1644 Related CVEs: CVE-2019-14540 CVE-2019-16335 CVE-2019-16942 CVE-2019-16943 CVE-2019-17531 Table of contents Symptom & Impact Environment & Reproduction Root Cause Analysis Quick Triage Step-by-Step Diagnosis Solution – Primary Fix Solution – Alternative […]

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