CSV Formula Injection Vulnerability in Shlink by Shlinkio
CVE-2026-18738

5.1MEDIUM

Key Information:

Vendor

Shlinkio

Status
Shlink
Vendor
CVE Published:
3 August 2026

What is CVE-2026-18738?

Shlink versions between 5.0.0 and 5.1.5 possess a CSV formula injection issue that enables unauthenticated remote attackers to inject malicious spreadsheet formulas into visit data exports. By manipulating headers such as User-Agent or Referer with characters that trigger formulas (like =, +, -, or @), an attacker can send specially crafted requests to any short URL. This facilitates the insertion of DDE or WEBSERVICE payloads into CSV outputs, which could compromise an administrator's client machine upon opening the CSV file in a spreadsheet application that executes these formulas.

Affected Version(s)

Shlink 5.0.0 <= 5.1.5

References

https://github.com/theopaid/CSV-formula-injection-in-visi...
vendor-advisory
https://github.com/shlinkio/shlink
product
https://www.vulncheck.com/advisories/shlink-csv-formula-i...
third-party-advisory

CVSS V4

Score:
5.1
Severity:
MEDIUM
Confidentiality:
None
Integrity:
Low
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Theodosis Paidakis
.