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Maven
Not in CISA KEV
HIGH severity

GHSA-p6xc-xr62-6r2g

HIGH

GHSA-p6xc-xr62-6r2g is a high-severity (CVSS 8.6) Improper Input Validation vulnerability in org.apache.logging.log4j:log4j-core. 4 public exploit references exist, so weaponization risk is real. O3 Security confirms whether GHSA-p6xc-xr62-6r2g is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Apache Log4j2 vulnerable to Improper Input Validation and Uncontrolled Recursion

Also known asCVE-2021-45105
Published
Dec 18, 2021
Updated
Jun 9, 2026
Affected
7 pkgs
Patched
7 / 7
Exploits
4 known
Exploitation data as of Aug 27, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-p6xc-xr62-6r2g.

EPSS Exploitation Probability

via FIRST.org ↗
100.0%probability of exploitation in next 30 days
Very High Risk0.00%
Lower risk than most CVEs100th percentile — riskier than 100% of all scored CVEsHighest risk
55.3%70.2%85.1%100.0%65.6%100.0%Feb 26Jun 26Aug 26

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

How urgent is this, really

GHSA-p6xc-xr62-6r2g plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE sits: patch-first territory.

Where this sits among everything scored

Of 368,770 CVEs with a current EPSS score, this one falls in the ≥ 90% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.

Real-World Exposure

7 pkgs affected
org.apache.logging.log4j:log4j-coreorg.apache.logging.log4j:log4j-coreorg.apache.logging.log4j:log4j-coreorg.ops4j.pax.logging:pax-logging-log4j2org.ops4j.pax.logging:pax-logging-log4j2org.ops4j.pax.logging:pax-logging-log4j2org.ops4j.pax.logging:pax-logging-log4j2

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

Apache Log4j2 versions 2.0-alpha1 through 2.16.0 (excluding 2.12.3) did not protect from uncontrolled recursion from self-referential lookups. This allows an attacker with control over Thread Context Map data to cause a denial of service when a crafted string is interpreted. This issue was fixed in Log4j 2.17.0 and 2.12.3.

Affected packages

Only the org.apache.logging.log4j:log4j-core package is directly affected by this vulnerability. The org.apache.logging.log4j:log4j-api should be kept at the same version as the org.apache.logging.log4j:log4j-core package to ensure compatability if in use.

Affected Packages

7 total 7 fixed
EcosystemPackageVulnerable rangeFix
Mavenorg.apache.logging.log4j:log4j-core2.4.0&&< 2.12.32.12.3
Mavenorg.apache.logging.log4j:log4j-core2.13.0&&< 2.17.02.17.0
Mavenorg.apache.logging.log4j:log4j-coreall versions2.3.1
Mavenorg.ops4j.pax.logging:pax-logging-log4j21.8.0&&< 1.9.21.9.2
Mavenorg.ops4j.pax.logging:pax-logging-log4j21.10.0&&< 1.10.91.10.9
Mavenorg.ops4j.pax.logging:pax-logging-log4j21.11.0&&< 1.11.121.11.12
Exploits & PoCs
4

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

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-core. 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-core to 2.12.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-p6xc-xr62-6r2g 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 GHSA-p6xc-xr62-6r2g 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 GHSA-p6xc-xr62-6r2g. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

Red Hat Product Security has performed an analysis of this flaw and has classified the Attack Complexity(AC) as High because there are multiple factors involved which are beyond attacker's control: - The application has to use the logging configuration using a Context Map Lookup (for example, $${ctx:loginId}) which is…

Frequently Asked Questions

Apache Log4j2 versions 2.0-alpha1 through 2.16.0 (excluding 2.12.3) did not protect from uncontrolled recursion from self-referential lookups. This allows an attacker with control over Thread Context Map data to cause a denial of service when a crafted string is interpreted. This issue was fixed in Log4j 2.17.0 and 2.12.3. # Affected packages Only the `org.apache.logging.log4j:log4j-core` package is directly affected by this vulnerability. The `org.apache.logging.log4j:log4j-api` should be kept at the same version as the `org.apache.logging.log4j:log4j-core` package to ensure compatability i
O3 Security · Impact-Aware SCA

Is GHSA-p6xc-xr62-6r2g in your dependencies?

O3 detects GHSA-p6xc-xr62-6r2g across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

GHSA-p6xc-xr62-6r2g: log4j-core Denial of… | O3 Security