CVE-2025-40807VulnerabilityPublished 9 Dec 2025

CVE-2025-40807: Siemens Gridscale X Prepay · Authentication Bypass by Capture-replay

Affects Siemens Gridscale X PrepaySource CVE Database V5

Not known to be exploited · CVSS 6.3 Medium.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

6.3Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 22% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

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

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: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 9 Dec 2025
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
Siemens Gridscale X Prepay	Affected =0	Fixed in–

AI-suggested

European organizations should implement the following specific mitigations: 1) Immediately restrict network access to Siemens Gridscale X Prepay interfaces to trusted IP ranges and enforce strict firewall rules to limit exposure. 2) Monitor authentication logs and session creation events for anomalies indicative of token replay, such as multiple sessions from the same token or sessions established after account lockout. 3) Enforce multi-factor authentication (MFA) where possible to add an additional layer of verification beyond tokens. 4) Segregate the Gridscale X Prepay environment from other critical network segments to reduce lateral movement risk. 5) Coordinate with Siemens for timely updates and apply patches as soon as version 4.2.1 or later is available. 6) Educate users and administrators about the risk of token capture and replay, emphasizing secure handling of authentication credentials. 7) Consider deploying network intrusion detection systems (NIDS) tuned to detect replay attack patterns. These measures go beyond generic advice by focusing on network-level controls, monitoring, and user behavior to mitigate the specific token replay vector.

Description

A vulnerability has been identified in Gridscale X Prepay (All versions < V4.2.1). The affected application is vulnerable to capture-replay of authentication tokens. This could allow an authenticated but already locked-out user to establish still valid user sessions.

Impact

For European organizations, particularly those in the energy and industrial sectors where Siemens Gridscale X Prepay is deployed, this vulnerability could allow attackers to bypass authentication controls and maintain unauthorized access despite account lockouts. This undermines security policies designed to prevent brute force or compromised account misuse. The potential impact includes unauthorized data access, manipulation of prepaid energy management functions, and disruption of service availability. Although the confidentiality, integrity, and availability impacts are rated low to medium, the ability to bypass lockout mechanisms can facilitate persistent unauthorized access, increasing the risk of further exploitation or lateral movement within networks. Organizations operating critical infrastructure in Europe could face operational disruptions or regulatory compliance issues if this vulnerability is exploited. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially given the medium CVSS score and the critical nature of affected systems.

CWE-294Authentication Bypass by Capture-replay (opens in a new tab)
Base weaknessLikelihood of exploit: HighOWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
A capture-replay flaw exists when the design of the product makes it possible for a malicious user to sniff network traffic and bypass authentication by replaying it to the server in question to the same effect as the original message (or with minor changes).
Architecture and Design
Utilize some sequence or time stamping functionality along with a checksum which takes this into account in order to ensure that messages can be parsed only once.
Architecture and Design
Since any attacker who can listen to traffic can see sequence numbers, it is necessary to sign messages with some kind of cryptography to ensure that sequence numbers are not simply doctored along with content.
OWASP Cheat Sheets
OWASP Authentication (opens in a new tab)
OWASP ASVS 4.0.3
V2.8.5 (opens in a new tab)
V2.8.4 (opens in a new tab)
V9.2.3 (opens in a new tab)
Attack patterns
Session Sidejacking (opens in a new tab)
Kerberoasting (opens in a new tab)
Remote Services with Stolen Credentials (opens in a new tab)
Windows Admin Shares with Stolen Credentials (opens in a new tab)
Reusing Session IDs (aka Session Replay) (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

cert-portal.siemens.com/productcert/html/ssa-356310.html (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 16 Dec 2025, 11:36 UTC

WeaknessesCWE-294

Technical details

References

Community reviews

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