SonicWall SonicOS Improper Access Control Vulnerability
CVE-2024-40766 is a security vulnerability in SonicWall SonicOS, added to CISA KEV on September 9, 2024. Patch order: first of four. Known ransomware use: yes.
What is CVE-2024-40766?
SonicWall SonicOS contains an improper access control vulnerability that could lead to unauthorized resource access and, under certain conditions, may cause the firewall to crash.
Known to be used in ransomware campaigns. Active threat actors have chained this vulnerability into ransomware operations — treat patching as a same-week priority, not a "next maintenance window" task. The fix is the same one below; the urgency is higher.
VulnCheck tracked exploitation 139 days before CISA's KEV listing. VulnCheck's broader catalog of in-the-wild exploitation evidence picked this up before it landed on CISA's formal list. Per-CVE fact about this entry; not a population claim about lead time in general.
Who is affected by CVE-2024-40766?
Affects anyone whose network is fronted by a SonicWall firewall or SSL VPN. The device sits at the edge between your office and the internet and authenticates remote workers — exploitation typically means an attacker reaches inside without needing a user credential.
What should I do about CVE-2024-40766?
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
If you don't have someone in-house to verify the patch deployed across every endpoint — or you're not sure whether you're affected — that's exactly the kind of triage we do. Request a free review.
Insurance readiness
Your insurer will ask if this is patched.
Unpatched entries on CISA's Known Exploited Vulnerabilities list are exactly what cyber-insurance carrier questionnaires probe for, and knowing which controls they check is how you keep a renewal from stalling.
Get the free carrier questionnaire →Severity
CVSS base score: 9.8 — CRITICAL
Weakness classification: CWE-284
CISA due date
CISA's listed due date: September 30, 2024.
Federal civilian agencies work under CISA's Binding Operational Directive 26-04, which replaced BOD 22-01 on June 10, 2026. It sets the deadline for each affected system by:
- How exposed that system is to the internet
- Whether the attack can be automated
- How much control it gives an attacker
Its table gives catalogued vulnerabilities 3 or 14 days.
None of this binds a private business, but treat the date as a strong recommendation, especially if you handle regulated data (HIPAA, GLBA, ABA model rules).
EPSS
EPSS score: 18.4% — higher than 97% of all scored CVEs.
EPSS estimates the probability of exploitation activity in the next 30 days. Every entry on this site is already confirmed exploited, so read it as relative urgency among the things you still have open, not as permission to wait.
Other exploited SonicWall SonicOS entries
More CISA KEV entries for SonicWall SonicOS. Same product line, same actively-exploited status.
Source
This entry comes from CISA's Known Exploited Vulnerabilities catalog, public US-Government data we pull daily. The plain-language framing and the what-to-do guidance above are ours. View the original entry on cisa.gov.