VulnerabilityPublished 18 Mar 2026

CVE-2026-22320: Phoenix Contact FL SWITCH 2005 · Stack-based Buffer Overflow

Affects Phoenix Contact FL SWITCH 2005Source CVE Database V5

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Not known to be exploited · CVSS 6.5 Medium : upgrade to 3.53 when convenient.

Data as of 30 Oct 2026, 20:25 UTC

CVSS 3.1 base score

6.5Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 26% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3.53

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade FL to 3.53.

Affected software

Product	Affected	Fixed in
Phoenix ContactFL SWITCH 2005	Affected <3.53	Fixed in 3.53
Phoenix ContactFL SWITCH 2008	Affected <3.53	Fixed in 3.53
Phoenix ContactFL SWITCH 2016	Affected <3.53	Fixed in 3.53
Phoenix ContactFL SWITCH 2105	Affected <3.53	Fixed in 3.53
Phoenix ContactFL SWITCH 2108	Affected <3.53	Fixed in 3.53
Phoenix ContactFL SWITCH 2116	Affected <3.53	Fixed in 3.53

AI-suggested

To mitigate this vulnerability effectively, organizations should implement strict access controls on Telnet and SSH interfaces of Phoenix Contact FL SWITCH 2005 devices, limiting access to trusted administrators only and preferably restricting access to management VLANs or secure jump hosts. Disabling Telnet entirely in favor of more secure management protocols is recommended. Network segmentation should isolate these switches from untrusted networks to reduce exposure. Monitoring and logging of TFTP command usage and unusual filename inputs can provide early detection of exploitation attempts. Since no patches are currently available, consider deploying compensating controls such as rate limiting or command filtering on the CLI if supported. Regularly check with Phoenix Contact for firmware updates or security advisories addressing this vulnerability. Conduct vulnerability scanning and penetration testing focused on these devices to identify potential exploitation attempts. Finally, prepare incident response plans to quickly recover from potential denial of service conditions affecting network management.

Description

A stack-based buffer overflow in the CLI's TFTP file‑transfer command handling allows a low-privileged attacker with Telnet/SSH access to trigger memory corruption by supplying unexpected or oversized filename input. Exploitation results in the corruption of the internal buffer, causing the CLI and web dashboard to become unavailable and leading to a denial of service.

Impact

The primary impact of this vulnerability is a denial of service condition on Phoenix Contact FL SWITCH 2005 devices. Organizations relying on these switches for network infrastructure could experience outages of the CLI and web dashboard management interfaces, impairing their ability to manage and monitor network operations. This could delay incident response and maintenance activities, potentially affecting operational continuity. Since the vulnerability requires only low-privileged Telnet or SSH access, attackers who have gained limited access to the device could escalate disruption without needing higher privileges or user interaction. While confidentiality and integrity are not directly impacted, the loss of availability in critical network infrastructure components can have cascading effects on industrial control systems, manufacturing environments, or enterprise networks that depend on these switches. The lack of known exploits reduces immediate risk but does not eliminate the threat, especially given the absence of patches. Organizations with these devices in critical roles face moderate operational risk until remediation is applied.

CWE-121Stack-based Buffer Overflow (opens in a new tab)
Variant weaknessLikelihood of exploit: HighCWE Top 25 (2025): #14
The product writes past the end of a buffer that was allocated on the stack.
Operation · Build and Compilation · Environment Hardening
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index…
Architecture and Design
Use an abstraction library to abstract away risky APIs. Not a complete solution.
Implementation
Implement and perform bounds checking on input.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

certvde.com/de/advisories/VDE-2025-104 (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 18 Mar 2026, 07:58 UTC

WeaknessesCWE-121

Technical details

References

Community reviews

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