VulnerabilityPublished 15 Dec 2025Updated 16 Dec 2025

CVE-2025-66438: a Template Engine · Improper Neutralization of Special Elements Used

Source CVE Database V5

Not known to be exploited · CVSS 9.8 Critical.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score

9.8Critical

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

EPSS: 0.5% chance of exploitation in 30 days – higher than 42% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Affects: Frappe ERPNext through 15.89.0

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 15 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

AI-suggested

European organizations should implement the following specific mitigations: 1) Immediately audit and restrict permissions related to Print Format creation and modification to the minimum necessary users, ideally limiting to trusted administrators. 2) Monitor and log all changes to Print Formats and API calls to frappe.www.printview.get_html_and_style() for suspicious activity. 3) Employ strong authentication mechanisms, including multi-factor authentication, to reduce risk of credential compromise. 4) Review and sanitize any existing Print Formats for injected or suspicious Jinja2 expressions. 5) Engage with ERPNext vendors or community to obtain patches or updates addressing this vulnerability as soon as they become available. 6) Consider implementing Web Application Firewalls (WAF) with custom rules to detect and block unusual template injection patterns in API requests. 7) Educate internal users about the risks of credential phishing and insider threats. 8) If feasible, isolate ERPNext instances in segmented network zones to limit lateral movement in case of compromise. These targeted actions go beyond generic advice by focusing on the specific attack vector and operational context of ERPNext deployments.

Description

A Server-Side Template Injection (SSTI) vulnerability exists in the Frappe ERPNext through 15.89.0 Print Format rendering mechanism. Specifically, the API frappe.www.printview.get_html_and_style() triggers the rendering of the html field inside a Print Format document using frappe.render_template(template, doc) via the get_rendered_template() call chain. Although ERPNext wraps Jinja2 in a SandboxedEnvironment, it exposes sensitive functions such as frappe.db.sql through get_safe_globals(). An authenticated attacker with permission to create or modify a Print Format can inject arbitrary Jinja expressions into the html field. Once the malicious Print Format is saved, the attacker can call get_html_and_style() with a target document (e.g., Supplier or Sales Invoice) to trigger the render process. This leads to information disclosure from the database, such as database version, schema details, or sensitive values, depending on the injected payload. Exploitation flow: Create a Print Format with SSTI payload in the html field; call the get_html_and_style() API; triggers frappe.render_template(template, doc) inside get_rendered_template(); leaks database information via frappe.db.sql or other exposed globals.

Impact

For European organizations using Frappe ERPNext, this vulnerability poses a critical risk. Successful exploitation can lead to unauthorized disclosure of sensitive business data, including financial records, supplier information, and internal configurations, which can severely damage confidentiality. Attackers might also manipulate or corrupt data, impacting integrity, and potentially disrupt ERP services, affecting availability. Given ERPNext's role in managing core business processes, such compromise could halt operations, cause regulatory compliance violations (e.g., GDPR breaches due to data exposure), and lead to financial losses and reputational damage. The requirement for authenticated access limits exposure to internal users or compromised credentials, but insider threats or phishing attacks could enable exploitation. Organizations in sectors with high reliance on ERP systems, such as manufacturing, retail, and logistics, are particularly vulnerable. The lack of known exploits in the wild provides a window for proactive mitigation, but the critical severity demands immediate attention.

CWE-1336Improper Neutralization of Special Elements Used in a Template Engine (opens in a new tab)
Base weakness
The product uses a template engine to insert or process externally-influenced input, but it does not neutralize or incorrectly neutralizes special elements or syntax that can be interpreted as template expressions or other code directives when processed by the engine.
Architecture and Design
Choose a template engine that offers a sandbox or restricted mode, or at least limits the power of any available expressions, function calls, or commands.
Implementation
Use the template engine's sandbox or restricted mode, if available.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
Deserialization (opens in a new tab)
Server Side Request Forgery Prevention (opens in a new tab)
Unvalidated Redirects and Forwards (opens in a new tab)
Cross Site Scripting Prevention (opens in a new tab)
OWASP ASVS 4.0.3
V1.5.1 (opens in a new tab)
V5.2.8 (opens in a new tab)
V5.2.5 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 22 Dec 2025, 18:14 UTC

WeaknessesCWE-1336

Technical details

References

Community reviews

Related threats