CVE-2026-18738 Shlink CSV Formula Injection via Visit Export CLI
Unauthenticated attackers can inject malicious formulas into CSV exports, leading to code execution on administrators' machines when files are opened.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-18738?
CVE-2026-18738 is a medium-severity code injection vulnerability in shlinkio Shlink, published on 3 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-1236
Which versions are affected by CVE-2026-18738?
How do I fix CVE-2026-18738?
No fix has been published for CVE-2026-18738 yet. Limit exposure of the affected software until one is available.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-18738 being exploited?
There is no known exploitation of CVE-2026-18738 in the wild and no public exploit code.
Sources
Also known as GHSA-ghrv-q878-w45x.