VulnerabilityPublished 23 Jun 2025

CVE-2025-6518: pyspur · Template Injection

Affects pyspurSource CVE Database V5

Not known to be exploited · CVSS 5.3 Medium.

Data as of 26 Oct 2026, 09:08 UTC

CVSS 4.0 base score

5.3Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 32% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P

Base metrics

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: Low
User Interaction: None
Vulnerable system confidentiality: Low
Vulnerable system integrity: Low
Vulnerable system availability: Low
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Threat metrics

Exploit Maturity: POC

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

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, 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: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system 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 Vulnerable System.
Vulnerable system 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 to the Vulnerable System.
Vulnerable system 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 Vulnerable System 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 Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.
Exploit Maturity: POC: Based on threat intelligence sources each of the following must apply: · Proof-of-concept is publicly available · No knowledge of reported attempts to exploit this vulnerability · No knowledge of publicly available solutions used to simplify attempts to exploit the vulnerability

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 23 Jun 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 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
PyPIpyspur`pkg:pypi/pyspur`Other threats	Affected =0.1.0 =0.1.1 =0.1.2 =0.1.3 =0.1.4 =0.1.5 =0.1.6 =0.1.7 =0.1.8 =0.1.9 =0.1.10 =0.1.11 =0.1.12 =0.1.13 =0.1.14 =0.1.15 =0.1.16 =0.1.17 =0.1.18	Fixed in–

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

AI-suggested

1. Immediate upgrade: Organizations should update pyspur to a version beyond 0.1.18 once a patched release is available from PySpur-Dev. 2. Input validation: Implement strict input validation and sanitization on all user-supplied data that is passed to template rendering functions, specifically targeting special template syntax characters or sequences. 3. Template sandboxing: Configure Jinja2 environment to use sandboxed execution modes or restrict template capabilities to minimize potential damage from malicious templates. 4. Network controls: Restrict access to services exposing pyspur functionality to trusted networks or authenticated users where possible, even though the vulnerability does not require authentication. 5. Monitoring and detection: Deploy monitoring for unusual template rendering errors, unexpected code execution patterns, or anomalous user_message inputs indicative of exploitation attempts. 6. Incident response readiness: Prepare to respond to potential exploitation by having logs and forensic data collection enabled on systems running pyspur. 7. Dependency management: Review and audit all dependencies related to pyspur and Jinja2 to ensure no other related vulnerabilities exist. 8. Security awareness: Educate developers and system administrators about the risks of template injection and secure coding practices around template engines.

Description

A vulnerability was found in PySpur-Dev pyspur up to 0.1.18. It has been classified as critical. Affected is the function SingleLLMCallNode of the file backend/pyspur/nodes/llm/single_llm_call.py of the component Jinja2 Template Handler. The manipulation of the argument user_message leads to improper neutralization of special elements used in a template engine. It is possible to launch the attack remotely. The exploit has been disclosed to the public and may be used.

Impact

For European organizations using pyspur, especially those integrating it into automated workflows or AI-driven systems that rely on Jinja2 templating, this vulnerability could lead to unauthorized code execution or data exposure. The medium severity suggests that while the impact is not catastrophic, it still poses a significant risk to confidentiality and integrity of data processed by pyspur. Organizations in sectors such as technology, research, and AI development that adopt pyspur for language model interfacing or template rendering could face disruption or data compromise. The remote exploitability without authentication increases the attack surface, making exposed services attractive targets. Additionally, if pyspur is embedded in larger systems or pipelines, exploitation could cascade, affecting broader infrastructure. The lack of known exploits in the wild currently reduces immediate risk, but the public disclosure means attackers may develop exploits soon. European organizations with limited patch management or monitoring capabilities may be particularly vulnerable to exploitation attempts. The vulnerability could also be leveraged as a foothold for lateral movement or further attacks within networks if exploited successfully.

References

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