Threats / SonicWall / CVE-2021-20038
CVE-2021-20038
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
SonicWall SMA 100 Appliances vulnerability
SonicWall SMA 100 Appliances contain an unauthenticated stack-based buffer overflow vulnerability enabling remote code execution without authentication.
Verdict
Today item, not a backlog item.
This vulnerability poses critical risk due to unauthenticated remote exploitation capability, high EPSS score, and confirmed active exploitation in ransomware campaigns. Immediate patching is required for all affected appliances.
CISA KEV Yes · 2022-01-283Ransomware use Flagged3EPSS 0.99912 (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
12 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 2022-01-28), flagged for known ransomware use.
Probability (EPSS)
EPSS 0.99912 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: SonicWall, SMA 100 Appliances. Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-121 Stack-based Buffer Overflow — weakness family: Memory safety.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 send a crafted network request to the SMA 100 appliance without credentials, triggering a stack buffer overflow.
Business
The organization's perimeter security appliance becomes a direct attack vector accessible to any internet-connected threat actor.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I overflow the stack buffer to inject and execute arbitrary code on the appliance with system privileges.
Business
Attackers gain complete control of the security gateway, enabling lateral movement into the internal network and data exfiltration.
3
Lateral reach — past segmentation narrative 3
Attacker
I establish persistent access and deploy ransomware payloads across the compromised network infrastructure.
Business
Critical business systems are encrypted and held for ransom, resulting in operational shutdown and potential financial extortion.
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