What’s Vulnerable › Vulnerabilities

CVE-2026-18738: Shlink CSV Formula Injection via Visit Export CLI

• Severity: medium (CVSS 4.7 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-03 · updated 2026-10-23
• Weakness: CWE-1236

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.

Affected products

• shlinkio Shlink: all versions

References

• https://github.com/shlinkio/shlink
• https://github.com/theopaid/CSV-formula-injection-in-visit-exports-shlink-
• https://www.vulncheck.com/advisories/shlink-csv-formula-injection-via-visit-export-cli

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