Threats / Apache / CVE-2021-45046
CVE-2021-45046
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Apache Log4j2 vulnerability
Apache Log4j2 contains a deserialization vulnerability in the Thread Context Lookup Pattern due to incomplete remediation of CVE-2021-44228, enabling remote code execution in non-default configurations.
Verdict
Today item, not a backlog item.
This vulnerability allows unauthenticated remote code execution through crafted input to the Thread Context Lookup Pattern. The incomplete fix of the original Log4j2 flaw leaves a secondary attack vector accessible in certain deployments, with active exploitation and ransomware campaigns documented.
CISA KEV Yes · 2023-05-013Ransomware use Flagged3EPSS 0.99977 (verify live)4Exploit Weaponized · public PoC5
01
Is it exploitable?
— the evidence, ranked above the scoreExploit available
Fully weaponized — public exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
Reported exploitation
26 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-05-01), flagged for known ransomware use.
Probability (EPSS)
EPSS 0.99977 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: Apache, Log4j2. Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-917 Expression Language Injection — weakness family: Injection.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious input string containing a Thread Context Lookup Pattern expression that triggers deserialization of untrusted data.
Business
An attacker gains arbitrary code execution on servers running vulnerable Log4j2 versions, enabling data theft, system compromise, or lateral movement.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I deliver the payload through application logging mechanisms that process user-controlled input without proper sanitization.
Business
The organization's infrastructure becomes a staging point for ransomware deployment or persistent backdoor installation across the network.
3
Lateral reach — past segmentation narrative 3
Attacker
I establish command and control channels to exfiltrate sensitive data or encrypt critical systems for extortion.
Business
The organization faces operational disruption, financial loss from ransom demands, regulatory penalties, and reputational damage from data breaches.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05