Security Hardening

Ubuntu 20.04 — libgcrypt20 — multiple vulnerabilities (2 CVEs) — patch and remediation guide — diagnosis and fix on Ubuntu 20.04

Ubuntu 20.04 — libgcrypt20 — multiple vulnerabilities (2 CVEs) — patch and remediation guide

🟢 Low   ⏱ 5–15 min  Last verified: 18 October 2021 Affected versions: Ubuntu 20.04 (focal) 📖 ~4 min read  •  Source: Ubuntu Security Notice USN-5080-1 Related CVEs: CVE-2021-33560 CVE-2021-40528 Upstream summary: It was discovered that Libgcrypt incorrectly handled ElGamal encryption. An attacker could possibly use this issue to recover sensitive information. Table of contents […]

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openSUSE Tumbleweed — python36 — multiple vulnerabilities (5 CVEs) — patch and remediation guide — diagnosis and fix on openSUSE Tumbleweed

openSUSE Tumbleweed — python36 — multiple vulnerabilities (5 CVEs) — patch and remediation guide

🟠 High   ⏱ 15–60 min  Last verified: 25 May 2026 Affected versions: openSUSE Tumbleweed 📖 ~4 min read  •  Source: SUSE advisory openSUSE-SU-2020:0931-1 (see also SUSE bugzilla) Related CVEs: CVE-2020-14422 CVE-2020-27619 CVE-2014-2667 CVE-2018-20406 CVE-2021-3426 Upstream summary: Lib/ipaddress.py in Python through 3.8.3 improperly computes hash values in the IPv4Interface and IPv6Interface classes, which might allow […]

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

Oracle Linux 8 — openssl — vulnerability — patch and remediation guide (ELSA-2021-9561)

🟡 Medium   ⏱ 10–30 min  Last verified: 18 October 2021 Affected versions: Oracle Linux 8 📖 ~4 min read  •  Source: ELSA advisory ELSA-2021-9561 Related CVEs: CVE-2021-23841 CVE-2021-23840 Table of contents Symptom & Impact Environment & Reproduction Root Cause Analysis Quick Triage Step-by-Step Diagnosis Solution – Primary Fix Solution – Alternative Approaches Verification & […]

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

Oracle Linux 8 — thunderbird — vulnerability — patch and remediation guide (ELSA-2021-4130)

🟠 High   ⏱ 15–60 min  Last verified: 18 October 2021 Affected versions: Oracle Linux 8 📖 ~4 min read  •  Source: ELSA advisory ELSA-2021-4130 Related CVEs: CVE-2021-38506 CVE-2021-38504 CVE-2021-38503 CVE-2021-38507 CVE-2021-38509 CVE-2021-38508 Table of contents Symptom & Impact Environment & Reproduction Root Cause Analysis Quick Triage Step-by-Step Diagnosis Solution – Primary Fix Solution – […]

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

Oracle Linux 8 — kernel security, bug fix, and — enhancement update — new behaviour and fixes (ELSA-2021-4056)

🟠 High   ⏱ 15–60 min  Last verified: 17 October 2021 Affected versions: Oracle Linux 8 📖 ~4 min read  •  Source: ELSA advisory ELSA-2021-4056 Related CVEs: CVE-2020-36385 CVE-2021-3656 CVE-2021-0512 Table of contents Symptom & Impact Environment & Reproduction Root Cause Analysis Quick Triage Step-by-Step Diagnosis Solution – Primary Fix Solution – Alternative Approaches Verification […]

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Common Problems 117932

Hash Sum mismatch During apt update

🟡 Medium   ⏱ 5–30 min  Last verified: 17 October 2021 📖 ~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 & Cross-Refs References & Further […]

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How to Configure MAC Policies on FreeBSD 13 — step-by-step FreeBSD 13 tutorial on Progressive Robot

How to Configure MAC Policies on FreeBSD 13

Introduction How to Configure MAC Policies on FreeBSD 13 is a core administration task for any FreeBSD 13 server operator. FreeBSD 13 ships with the 15.0-RELEASE kernel, ZFS as the default root filesystem, Capsicum capability sandboxing improvements, and an updated ports tree. Unlike Linux distributions, FreeBSD uses rc(8) for service management, pf for packet filtering, […]

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Debian 11 — etherape — vulnerability — patch and remediation guide — diagnosis and fix on Debian 11

Debian 11 — etherape — vulnerability — patch and remediation guide

🟢 Low   ⏱ 5–15 min  Last verified: 17 October 2021 Affected versions: Debian 11 (bullseye) 📖 ~4 min read  •  Source: Debian Security Tracker Related CVEs: CVE-2011-3369 Upstream summary: The add_conversation function in conversations.c in EtherApe before 0.9.12 allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via […]

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