VulnerabilityPublished 11 Aug 2025

CVE-2025-55161: Stirling-PDF · Server-Side Request Forgery (SSRF)

Affects Stirling-PDFSource CVE Database V5

Not known to be exploited · public detection template (Nuclei) · CVSS 8.6 High : upgrade to 1.1.0 soon.

Data as of 26 Oct 2026, 09:15 UTC

CVSS 3.1 base score

8.6High

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

EPSS: 1.9% chance of exploitation in 30 days – higher than 80% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.1.0

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
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: 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: 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 11 Aug 2025
Detectable: evidence found.
nuclei template: Stirling-PDF SSRF via Markdown
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

Upgrade Stirling-PDF to 1.1.0.

Affected software

Product	Affected	Fixed in
Stirling-Tools Stirling-PDF	Affected <1.1.0	Fixed in 1.1.0

AI-suggested

Organizations should immediately upgrade Stirling-PDF to version 1.1.0 or later, where the SSRF vulnerability has been patched. Until the upgrade is applied, it is critical to implement network-level controls to restrict the application’s outbound HTTP requests to only trusted destinations, using firewall rules or proxy filtering. Application-level input validation should be enhanced to reject suspicious URLs or IP addresses, especially those pointing to internal network ranges (e.g., 10.0.0.0/8, 192.168.0.0/16, 127.0.0.0/8). Monitoring and logging of all outbound requests from the Stirling-PDF server should be enabled to detect anomalous or unexpected traffic patterns indicative of SSRF exploitation attempts. Additionally, organizations should conduct internal penetration testing focused on SSRF to identify any other potential weaknesses. Segmentation of the network hosting Stirling-PDF from sensitive internal systems can reduce the blast radius if exploitation occurs. Finally, ensure that all third-party tools integrated with Stirling-PDF are kept up to date and reviewed for similar vulnerabilities.

Description

Stirling-PDF is a locally hosted web application that performs various operations on PDF files. Prior to version 1.1.0, when using the /api/v1/convert/markdown/pdf endpoint to convert Markdown to PDF, the backend calls a third-party tool to process it and includes a sanitizer for security sanitization which can be bypassed and result in SSRF. This issue has been patched in version 1.1.0.

Impact

For European organizations using Stirling-PDF versions earlier than 1.1.0, this SSRF vulnerability poses a significant risk. Since Stirling-PDF is locally hosted, exploitation could allow attackers to pivot from the compromised application to internal network resources, potentially accessing sensitive data or internal APIs not exposed externally. This could lead to unauthorized data disclosure, including confidential documents or internal services. The confidentiality impact is high, as attackers can leverage SSRF to bypass network segmentation and access internal-only endpoints. Integrity and availability impacts are lower but still present, as attackers might manipulate backend services or cause denial of service through crafted requests. European organizations in sectors such as finance, healthcare, legal, and government, which often handle sensitive PDF documents and rely on internal document processing tools, are particularly at risk. The lack of required authentication and user interaction increases the threat level, making automated exploitation feasible. Additionally, compliance with GDPR and other data protection regulations could be jeopardized if sensitive data is exposed due to this vulnerability.

CWE-918Server-Side Request Forgery (SSRF) (opens in a new tab)
Base weaknessCWE Top 25 (2025): #22OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.
OWASP Cheat Sheets
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)
DOM based XSS Prevention (opens in a new tab)
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V12.6.1 (opens in a new tab)
V5.2.6 (opens in a new tab)
Attack patterns
Server Side Request Forgery (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 19 Aug 2025, 01:43 UTC

Public exploits and detectiona Nuclei detection template

WeaknessesCWE-918

Technical details

References

Community reviews

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