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CriticalCISA KEVExploited in the wildPublic exploit

SQL Injection in SonicWall SMA100 SSL VPN

IdentifiersCVE-2021-20016CWE-89· Improper Neutralization of Special…

CVE-2021-20016 is a critical SQL injection vulnerability in SonicWall Secure Mobile Access (SMA) 100 series / SSLVPN products affecting SMA100 build version 10.x. The flaw allows a remote, unauthenticated attacker to submit a specially crafted query to the appliance and perform unauthorized SQL queries against the backend data store. According to the provided content, successful exploitation can expose sensitive appliance data including usernames, passwords, and session-related information. Multiple sources in the content describe the issue as affecting unpatched SMA 100 series remote access products and note that SonicWall patched the vulnerability in February 2021.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows unauthorized access to sensitive authentication and session data stored by the appliance, including usernames, passwords, and other session-related information. Because the target is a remote access/VPN platform, compromise of these data can enable follow-on intrusion activity, including initial access to victim environments. The provided content also notes reporting that the vulnerability was exploited in the wild by ransomware operators and affiliates, including activity associated with UNC2447, UNC2659, DARKSIDE/FiveHands operations, and that there was unconfirmed evidence it may have been used to disable MFA options on affected SonicWall VPN devices.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, reduce exposure of SMA 100 appliances by restricting access to trusted source IPs, minimizing or removing internet exposure where operationally feasible, enforcing MFA for VPN access, monitoring for suspicious access and session anomalies, rotating credentials that may have been exposed through the appliance, invalidating active sessions, and reviewing appliance configuration for unauthorized changes. Because the vulnerability can expose credential and session data, incident response should include credential resets and review for downstream compromise.

Remediation

Patch, then assume compromise.

Apply SonicWall’s vendor patch for CVE-2021-20016. The content states SonicWall patched the vulnerability in February 2021 and references PSIRT advisory SNWLID-2021-0001. Affected organizations should upgrade SMA 100 series appliances to the fixed firmware/builds specified by SonicWall and verify that no affected SMA100 build version 10.x systems remain exposed.
PUBLIC EXPLOITS

Exploits

1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos.

VALID 1 / 1 TOTALView more in app
sonicwall-audit-toolkitMaturityPoCVerified exploit

Repository purpose: a Python-based SonicWall “Security Audit Toolkit” plus a Docker CTF-style lab that simulates and (in solutions) exploits two critical SonicWall CVEs. Top-level structure: - sonicwall_audit.py: main orchestrator CLI that runs modules (ssl, cve, auth, web) against a target https://<host>:<port>, writes JSON/text reports to reports/. - validate_cves.py: standalone deep validators for CVE-2021-20038 and CVE-2024-53704 using non-destructive behavioral checks. - modules/: implementation of auditors/validators and report generation. - lab/: docker-compose lab with two containers: - cve-2021-20038: Apache + deliberately vulnerable 32-bit CGI binary /usr/lib/cgi-bin/sslvpnclient (and symlinks portal/welcome/etc). Protections disabled (no canary, execstack, no PIE, ASLR disabled in entrypoint) to make stack overflow exploitation feasible. - cve-2024-53704: Flask/Gunicorn SSLVPN simulator on 4433 with vulnerable swap cookie deserialization (conditional HMAC verification). - lab/exploits/: skeleton exploit templates (incomplete). - lab/solutions/: working exploits. Exploit capabilities present: 1) CVE-2024-53704 (auth bypass via cookie forgery): Working exploit forges a base64-encoded JSON session cookie named swap with {username, authenticated:true} and omits sig_version so the server skips HMAC verification. It then accesses /virtual-office/ and /dashboard to retrieve the flag. 2) CVE-2021-20038 (stack buffer overflow -> RCE): Working exploit crafts a URL-encoded query string payload to overflow a 4096-byte stack buffer in the CGI handler (strcpy of QUERY_STRING). Payload includes a NOP sled, null-free 32-bit x86 Linux shellcode that runs /bin//sh -c "cat /root/flag.txt", padding to offset 4100, and an attacker-chosen return address into the sled. Output is returned in the HTTP response body. Important distinction: the main toolkit modules and CVE validators are primarily scanners/validators and explicitly avoid destructive exploitation; the actual exploitation code is confined to the lab solution scripts intended for the local practice environment.

anir0yDisclosed Feb 23, 2026pythoncnetworklocal (docker lab)
EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
SonicwallSma 100 Firmwareoperating_system
SonicwallSma 200 Firmwareoperating_system
SonicwallSma 210 Firmwareoperating_system
SonicwallSma 400 Firmwareoperating_system
SonicwallSma 410 Firmwareoperating_system
SonicwallSma 500vhardware

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What this page doesn’t show

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Exposure mapping

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Threat actor evidence3

Every observed campaign linking this CVE to a named adversary.

Associated malware6

Malware families riding this exploit, with evidence and IOCs.

Detection signatures1

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity8

Community discussion across Reddit, Mastodon, and other social sources.