CVE-2026-22903VulnerabilityPublished 9 Feb 2026

CVE-2026-22903: WAGO 0852-1322 · Stack-based Buffer Overflow

Affects WAGO 0852-1322Source CVE Database V5

Not known to be exploited · CVSS 9.8 Critical.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

9.8Critical

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

EPSS: 0.7% chance of exploitation in 30 days – higher than 54% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
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: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
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: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to 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 9 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 2026-10-26.

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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC 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

Affected software

Product	Affected	Fixed in
WAGO0852-1322	Affected <=2.64	Fixed in–
WAGO0852-1328	Affected <=2.64	Fixed in–
WAGO0852-1322	Affected =2.64	Fixed in–
WAGO0852-1328	Affected =2.64	Fixed in–

AI-suggested

Since no official patches are currently available, European organizations should implement immediate compensating controls. Network segmentation is critical: isolate WAGO 0852-1322 devices within dedicated OT network zones with strict firewall rules limiting access to trusted management hosts only. Deploy intrusion detection/prevention systems (IDS/IPS) capable of detecting anomalous HTTP requests, especially those with unusually long cookies or malformed headers. Implement rate limiting and deep packet inspection on network gateways to block suspicious traffic patterns. Regularly audit and monitor device logs for signs of crashes or unusual behavior indicative of exploitation attempts. Where possible, disable or restrict HTTP access to the device management interface, or require VPN access with strong authentication. Engage with WAGO support channels to obtain firmware updates or security advisories. Additionally, conduct thorough asset inventories to identify all affected devices and prioritize remediation efforts. Establish incident response plans specific to OT environments to quickly contain and recover from potential exploitation. Finally, collaborate with national cybersecurity agencies and industry groups to share threat intelligence and mitigation strategies.

Description

CVE-2026-22903 is a critical stack-based buffer overflow vulnerability in the WAGO 0852-1322 device's modified lighttpd server. An unauthenticated remote attacker can exploit this by sending an HTTP request with an excessively long SESSIONID cookie, causing the server to crash and potentially allowing remote code execution. The vulnerability arises due to missing stack protections, making exploitation easier and more impactful. This flaw affects the availability, integrity, and confidentiality of the device and connected systems. No patches are currently available, and no known exploits are reported in the wild yet. European organizations using WAGO 0852-1322 devices, especially in industrial automation and control systems, are at high risk. Mitigation requires network-level protections, strict input validation, and monitoring for anomalous HTTP requests. Countries with significant industrial automation sectors and WAGO market presence, such as Germany, France, and the Netherlands, are most likely to be affected. Given the critical CVSS score of 9.8, immediate attention and proactive defense measures are essential to prevent exploitation.

Impact

For European organizations, the impact of CVE-2026-22903 is significant, especially in sectors relying on industrial automation and control systems such as manufacturing, energy, transportation, and utilities. WAGO 0852-1322 devices are commonly used in programmable logic controllers (PLCs) and remote I/O modules, which are integral to operational technology (OT) environments. Exploitation could lead to denial of service, disrupting critical industrial processes and causing production downtime. More dangerously, remote code execution could allow attackers to manipulate control logic, alter sensor readings, or disable safety mechanisms, potentially causing physical damage or safety hazards. The confidentiality of sensitive operational data could also be compromised. Given the unauthenticated nature of the attack vector, threat actors could scan and exploit vulnerable devices remotely, increasing the risk of widespread incidents. The lack of available patches exacerbates the risk, forcing organizations to rely on compensating controls. The impact extends beyond individual organizations to national critical infrastructure, potentially affecting supply chains and public safety across Europe.

Summary

CVE-2026-22903 is a critical security vulnerability identified in the WAGO 0852-1322 device, which utilizes a modified version of the lighttpd web server. The vulnerability is a stack-based buffer overflow (CWE-121) triggered by an unauthenticated remote attacker sending an HTTP request containing an overly long SESSIONID cookie. This malformed input overflows a stack buffer due to insufficient input length validation and the absence of stack protection mechanisms such as stack canaries or ASLR in the affected server implementation. The overflow can cause the server process to crash, resulting in a denial of service. More critically, the lack of stack protections opens the door for remote code execution (RCE) by overwriting the return address or other control data on the stack. The vulnerability requires no authentication or user interaction, making it highly exploitable over the network. The affected product version is listed as 0.0.0, which likely indicates an initial or default firmware version, suggesting that all deployed devices with this firmware are vulnerable. No patches or mitigations have been published yet, and no known exploits are currently reported in the wild. The CVSS v3.1 base score is 9.8, reflecting the high impact on confidentiality, integrity, and availability, combined with the ease of exploitation. The vulnerability is particularly concerning for industrial control systems and automation environments where WAGO devices are deployed, as successful exploitation could lead to operational disruption or unauthorized control of critical infrastructure components.

CWE-121Stack-based Buffer Overflow (opens in a new tab)
Variant weaknessLikelihood of exploit: HighCWE Top 25 (2025): #14
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
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-2026-004 (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 16 Feb 2026, 13:29 UTC

WeaknessesCWE-121

Technical details

References

Community reviews

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