VulnerabilityPublished 22 Dec 2025

CVE-2025-26787: signserver · External Control of Critical State Data

Affects signserverSource CVE Database V5

Not known to be exploited · CVSS 4.7 Medium : upgrade to 7.2 when convenient.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score

4.7Medium

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

EPSS: 0.1% chance of exploitation in 30 days – higher than 4% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 7.2

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: High
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: High: The attacker is authorized with (i.e., requires) privileges that provide significant (e.g., administrative) control over the vulnerable component that could affect component-wide settings and files.
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 22 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 26 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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 com.keyfactor/signserver to 7.2.

Affected software

Product	Affected	Fixed in
Mavencom.keyfactor/signserver`pkg:maven/com.keyfactor/signserver`Other threats	Affected <7.2	Fixed in 7.2

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade immediately to Keyfactor SignServer version 7.2 or later, where the container startup logic has been corrected to prevent resetting access permissions on restarts.
Audit current SignServer container configurations and restart procedures to verify that access controls have not been inadvertently reset to 'allowany'.
Implement strict certificate issuance and revocation policies to minimize the risk of misuse of valid client certificates.
Monitor SignServer logs and access patterns for unusual connections or certificate operations that could indicate exploitation attempts.
Restrict network access to SignServer containers to trusted hosts and networks, reducing exposure to unauthorized clients.
Employ container orchestration best practices to control and audit container restarts, ensuring that security configurations persist across restarts.
Educate administrators on the importance of verifying access control settings after container restarts until the patch is applied.
Consider implementing additional authentication layers or network segmentation around SignServer deployments to limit potential attack vectors.

Description

An error in the SignServer container startup logic was found in Keyfactor SignServer versions prior to 7.2. The Admin CLI command used to configure Certificate access to the initial startup of the container sets a property of "allowany" to allow any user with a valid and trusted client auth certificate to connect. Admins can then set more restricted access to specific certificates. A logic error caused this admin CLI command to be run on each restart of the container instead of only the first startup as intended resetting the configuration to "allowany".

Impact

For European organizations, this vulnerability could lead to unauthorized access to certificate management functions within Keyfactor SignServer environments. Since certificates are foundational to securing communications, authenticating users, and enabling encryption, unauthorized access could compromise the confidentiality and integrity of sensitive data and communications. Attackers with valid client certificates could exploit the permissive 'allowany' setting to connect to the SignServer and potentially issue fraudulent certificates, revoke legitimate ones, or disrupt certificate services. This could undermine trust in digital identities, disrupt secure communications, and facilitate further attacks such as man-in-the-middle or impersonation attacks. Organizations in sectors with high reliance on PKI infrastructure—such as finance, government, telecommunications, and critical infrastructure—face elevated risks. The vulnerability also increases the attack surface during container restarts, which may occur frequently in cloud or container orchestration environments common in Europe. Although no exploits are known, the ease of exploitation is moderate since attackers must possess valid client certificates, but the resetting of access controls significantly lowers barriers to unauthorized access once inside the network or with compromised certificates.

CWE-642External Control of Critical State Data (opens in a new tab)
Class weaknessLikelihood of exploit: HighOWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
The product stores security-critical state information about its users, or the product itself, in a location that is accessible to unauthorized actors.
Architecture and Design
Understand all the potential locations that are accessible to attackers. For example, some programmers assume that cookies and hidden form fields cannot be modified by an attacker, or they may not consider that environment variables can be modified before a privileged program is invoked.
Architecture and Design · Attack Surface Reduction
Store state information and sensitive data on the server side only.
Architecture and Design
Store state information on the server side only. Ensure that the system definitively and unambiguously keeps track of its own state and user state and has rules defined for legitimate state transitions.
OWASP Cheat Sheets
Secure Design Principles (opens in a new tab)
Attack patterns
Accessing/Intercepting/Modifying HTTP Cookies (opens in a new tab)
Exploitation of Trusted Identifiers (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 22 Dec 2025, 18:40 UTC

WeaknessesCWE-642

Technical details

References

Community reviews

Related threats