VulnerabilityPublished 10 Jul 2026

CVE-2026-49865: Invoice PDF Rendering · Kimai Has Server-Side Request Forgery

Affects kimai/kimaiSource GCVE Database

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Not known to be exploited · CVSS 5.3 Medium : upgrade to 2.58.0 when convenient.

Data as of 30 Oct 2026, 11:52 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 28% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2.58.0

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

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

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: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent 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 Subsequent 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.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 10 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 30 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), 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 kimai/kimai to 2.58.0.

Affected software

Product	Affected	Fixed in
Packagistkimai/kimai	Affected <2.58.0	Fixed in 2.58.0

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

AI-suggested

Kimai 2.58.0 and later versions have mitigations that disable Markdown image rendering by converting them to HTML links instead. Additionally, Kimai uses a specialized HTTP client (`NoPrivateNetworkHttpClient`) for mPDF that blocks requests to private network addresses and other restricted URLs. Users should upgrade to version 2.58.0 or later to apply these fixes. Note that this change may cause backward compatibility issues if invoice or export templates rely on hosting images on the Kimai domain or internal IP addresses. Patch status: An official fix is available in Kimai 2.58.0.

Description

### Summary Kimai 2.56.0 contains a server-side request forgery vulnerability in its invoice PDF preview and generation workflow. If an attacker can control Markdown content that is later rendered into an invoice PDF, such as `Customer.invoiceText`, the server-side PDF renderer will fetch remote image URLs embedded in Markdown image syntax. This allows the application server to issue outbound requests to attacker-controlled or internal targets during PDF rendering. The behavior can be used for internal network probing, server-side reachability checks, and potentially follow-on exploitation depending on deployment environment and accessible internal services. ### Details The vulnerable behavior occurs in the invoice rendering chain when user-controlled Markdown is transformed into HTML and then rendered by mPDF. - First, customer invoice text is copied into the invoice model. . Second, the default PDF invoice template renders that field through the Markdown-to-HTML filter. - Third, `md2html` enables full Markdown rendering. - Although safe mode is enabled, the tested Markdown image syntax still survives into the rendered HTML chain in a form that causes the PDF renderer to fetch the image resource. - Finally, the HTML is handed to mPDF. The live test confirms that mPDF attempts to retrieve the remote image URL from the server side during PDF preview. This means the issue is not a template-injection problem but an SSRF condition caused by the rendering pipeline: - attacker-controlled Markdown - Markdown converted to HTML - HTML rendered by mPDF - mPDF fetches remote image resources from the server side *A PoC was provided, but removed for security reasons.* ### Impact This vulnerability allows an attacker who can influence invoice-rendered Markdown fields to cause the Kimai server to make outbound requests to arbitrary destinations. In real deployments, this can be used to probe internal services, test access to internal administrative or metadata endpoints, and confirm server-side reachability to attacker-controlled infrastructure. Depending on the environment, SSRF can also become a stepping stone toward more serious outcomes, such as triggering side effects on internal HTTP services or extracting sensitive information from services reachable only by the server. Because invoice generation is commonly performed by administrative or finance-related users, the feature is realistically reachable in business workflows. # Solution - Kimai does not allow to use markdown images any longer and converts them to HTML links instead - Kimai uses a specialized HttpClient for mPDF (called `NoPrivateNetworkHttpClient`), which prevents access to a variety of URLs, the full list can be fetched [from the documentation](https://www.kimai.org/documentation/pdf-templates.html#embedding-images) - This change can be a BC break, if someone used - the Kimai domain for hosting invoice or export template images - an internal IP for hosting invoice or export template images See https://www.kimai.org/en/security/ghsa-pj8j-p4g4-4vw8

Impact

An attacker able to influence invoice-rendered Markdown fields can cause the Kimai server to make arbitrary outbound HTTP requests. This can be used to probe internal network services, test access to internal administrative endpoints, and confirm server-side reachability to attacker-controlled infrastructure. Depending on deployment, this SSRF could lead to further exploitation such as triggering side effects on internal services or extracting sensitive information accessible only from the server. Since invoice generation is typically performed by administrative or finance users, the vulnerability is realistically exploitable in business workflows.

CWE-918Server-Side Request Forgery (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.
Implementation · Operation
If there is a known list of applications, IP, hostname, and/or domains to which the product is allowed to communicate, then use allowlists to ensure that outgoing requests are restricted to these known entities. The allowlists could be in the application code or possibly enforced by firewalls or network segmentation.
Implementation · Operation
If the product is expected to be able to connect to arbitrary IP addresses or domains, consider using a denylist that includes private network addresses, internal domain names, etc. The denylist could be in the application code or possibly enforced by firewalls or network segmentation.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
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).

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 11 Jul 2026, 10:08 UTC

WeaknessesCWE-918

Technical details

References

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