CVE-2026-18738: Shlink CSV Formula Injection via Visit Export CLI
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 Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-18738?
CVE-2026-18738 has a medium severity rating of 4.7.
How do I fix CVE-2026-18738?
To fix CVE-2026-18738, upgrade Shlink to version 5.1.6 or later.
What kind of attack does CVE-2026-18738 allow?
CVE-2026-18738 allows unauthenticated remote attackers to inject malicious spreadsheet formulas into exported visit data.
Which versions of Shlink are affected by CVE-2026-18738?
Shlink versions 5.0.0 through 5.1.5 are affected by CVE-2026-18738.
What are the entry points for the attack in CVE-2026-18738?
The entry points for the attack in CVE-2026-18738 include User-Agent, Referer, or request path headers that start with formula-triggering characters.