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Maven
Not in CISA KEV
LOW severity

CVE-2020-9488

LOW

CVE-2020-9488 is a low-severity (CVSS 3.7) CWE-295 vulnerability in org.apache.logging.log4j:log4j. O3 Security confirms whether CVE-2020-9488 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Improper validation of certificate with host mismatch in Apache Log4j SMTP appender

Also known asGHSA-vwqq-5vrc-xw9h
Published
Apr 27, 2020
Updated
Jul 8, 2026
Affected
6 pkgs
Patched
6 / 6
Exploits
None indexed
Exploitation data as of Jul 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Real-World Exposure

6 pkgs affected
org.apache.logging.log4j:log4jorg.apache.logging.log4j:log4j-coreorg.apache.logging.log4j:log4jorg.apache.logging.log4j:log4jorg.apache.logging.log4j:log4j-coreorg.apache.logging.log4j:log4j-core

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

Improper validation of certificate with host mismatch in Apache Log4j SMTP appender. This could allow an SMTPS connection to be intercepted by a man-in-the-middle attack which could leak any log messages sent through that appender. Fixed in Apache Log4j 2.12.3 and 2.13.1

Affected Packages

6 total 6 fixed
EcosystemPackageVulnerable rangeFix
Mavenorg.apache.logging.log4j:log4j2.13.0&&< 2.13.22.13.2
Mavenorg.apache.logging.log4j:log4j-core2.13.0&&< 2.13.22.13.2
Mavenorg.apache.logging.log4j:log4j2.4.0&&< 2.12.32.12.3
Mavenorg.apache.logging.log4j:log4jall versions2.3.2
Mavenorg.apache.logging.log4j:log4j-core2.4.0&&< 2.12.32.12.3
Mavenorg.apache.logging.log4j:log4j-coreall versions2.3.2

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.logging.log4j:log4j. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update org.apache.logging.log4j:log4j to 2.13.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-9488 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether CVE-2020-9488 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2020-9488. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

Improper validation of certificate with host mismatch in Apache Log4j SMTP appender. This could allow an SMTPS connection to be intercepted by a man-in-the-middle attack which could leak any log messages sent through that appender. Fixed in Apache Log4j 2.12.3 and 2.13.1
O3 Security · Impact-Aware SCA

Is CVE-2020-9488 in your dependencies?

O3 detects CVE-2020-9488 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

CVE-2020-9488: log4j (Low 3.7) | O3 Security