CVE-2026-22321 Stack-Based Buffer Overflow in CLI Login Username Handling over CLI
Unauthenticated attackers can cause a denial of service by sending oversized usernames to the CLI login, crashing the session thread.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-22321?
CVE-2026-22321 is a medium-severity memory corruption vulnerability in Phoenix Contact FL NAT 2008, published on 18 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A stack-based buffer overflow in the device's Telnet/SSH CLI login routine occurs when a unauthenticated attacker send an oversized or unexpected username input. An overflow condition crashes the thread handling the login attempt, forcing the session to close. Because other CLI sessions remain unaffected, the impact is limited to a low‑severity availability disruption.
Weakness: CWE-121
Which versions are affected by CVE-2026-22321?
How do I fix CVE-2026-22321?
No fix has been published for CVE-2026-22321 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-22321 being exploited?
There is no known exploitation of CVE-2026-22321 in the wild and no public exploit code.
Sources
Also known as GHSA-j66g-mfcw-hrf3.