CVE-2026-18738
Shlink CSV Formula Injection via Visit Export CLI
Description
Shlink versions 5.0.0 through 5.1.5 contain a CSV formula injection vulnerability that allows unauthenticated remote attackers to plant spreadsheet formulas into exported visit data by supplying malicious values in User-Agent, Referer, or request path headers beginning with formula-triggering characters such as =, +, -, or @. Attackers can craft a single unauthenticated request against any short URL to embed DDE or WEBSERVICE formula payloads into CSV cells, which are then executed on an administrator's client machine when the exported CSV file is opened in a spreadsheet application that evaluates formulas.
INFO
Published Date :
Aug. 3, 2026, 9:16 p.m.
Last Modified :
Oct. 23, 2026, 9:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | MEDIUM | MITRE-CVE | ||||
| CVSS 4.0 | MEDIUM | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update Shlink to a version later than 5.1.5.
- Implement input validation for User-Agent, Referer, and path.
- Sanitize exported data to prevent formula execution.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-18738.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-18738 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-18738
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-18738 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-18738 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Oct. 23, 2026
Action Type Old Value New Value Added Translation Title: Shlink de shlinkio, Description: Las versiones de Shlink 5.0.0 a 5.1.5 contienen una vulnerabilidad de inyección de fórmulas CSV que permite a atacantes remotos no autenticados insertar fórmulas de hoja de cálculo en los datos de visita exportados al proporcionar valores maliciosos en los encabezados User-Agent, Referer o de la ruta de solicitud que comienzan con caracteres que activan fórmulas, como =, +, - o @. Los atacantes pueden elaborar una única solicitud no autenticada contra cualquier URL corta para incrustar cargas útiles de fórmulas DDE o WEBSERVICE en celdas CSV, que luego se ejecutan en la máquina cliente de un administrador cuando el archivo CSV exportado se abre en una aplicación de hoja de cálculo que evalúa fórmulas. -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 04, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-18738', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-04T14:28:31.781240Z'} -
New CVE Received by [email protected]
Aug. 03, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'shlinkio', 'product': 'Shlink', 'versions': [{'status': 'affected', 'version': '5.0.0', 'versionType': 'git', 'lessThanOrEqual': '5.1.5'}], 'defaultStatus': 'affected'}] Added Description Shlink versions 5.0.0 through 5.1.5 contain a CSV formula injection vulnerability that allows unauthenticated remote attackers to plant spreadsheet formulas into exported visit data by supplying malicious values in User-Agent, Referer, or request path headers beginning with formula-triggering characters such as =, +, -, or @. Attackers can craft a single unauthenticated request against any short URL to embed DDE or WEBSERVICE formula payloads into CSV cells, which are then executed on an administrator's client machine when the exported CSV file is opened in a spreadsheet application that evaluates formulas. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N Added CWE CWE-1236 Added Reference https://github.com/shlinkio/shlink Added Reference https://github.com/theopaid/CSV-formula-injection-in-visit-exports-shlink- Added Reference https://www.vulncheck.com/advisories/shlink-csv-formula-injection-via-visit-export-cli