Authenticated service crash via oversized TFTP filename
Published Mar 18, 2026 · Updated Mar 18, 2026
Stack-based buffer overflow in Phoenix Contact FL SWITCH and FL NAT firmware before 3.53 allows remote authenticated users to crash management services. The CLI TFTP command accepts unexpected or oversized filename input into an internal stack buffer without rejecting input that exceeds its capacity. Low-privileged Telnet or SSH access is required; successful exploitation makes the CLI and web dashboard unavailable.
Summary
What happened
Stack-based buffer overflow in Phoenix Contact FL SWITCH and FL NAT firmware before 3.53 allows remote authenticated users to crash management services. The CLI TFTP command accepts unexpected or oversized filename input into an internal stack buffer without rejecting input that exceeds its capacity. Low-privileged Telnet or SSH access is required; successful exploitation makes the CLI and web dashboard unavailable.
The record
- CVE
- CVE-2026-22320
- Published
- Mar 18, 2026
- Updated
- Mar 18, 2026
- Vendor
- Phoenix Contact
- Product
- FL SWITCH 2204-2TC-2SFX
- Classifications
- CWE-121, T1499
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Mar 18, 2026CVE publishedPublication date reported by the CVE source.
- Mar 18, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0.0.0 <3.53
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo