What is CVE-2026-18738?

CVE-2026-18738 is a medium-severity vulnerability in Shlinkio Shlink, classified under Improper Neutralization of Formula Elements in a CSV File. CVSS score: 4.7/10. Published 2026-08-03.

How severe is CVE-2026-18738?

Medium severity. CVSS v3 base score is 4.7 out of 10.

Vulnerability in Shlinkio Shlink

CVE-2026-18738

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.

EPSS: 0.004 (31.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 4.7 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N.

Affected products

Shlinkio Shlink — versions 5.0.0

Weakness classification (CWE)

CWE-1236 — Improper Neutralization of Formula Elements in a CSV File

References

disclosure@vulncheck.com (product)
disclosure@vulncheck.com (vendor-advisory)
disclosure@vulncheck.com (third-party-advisory)

Frequently asked questions

What is CVE-2026-18738?: CVE-2026-18738 is a medium-severity vulnerability in Shlinkio Shlink, classified under Improper Neutralization of Formula Elements in a CSV File. CVSS score: 4.7/10. Published 2026-08-03.
How severe is CVE-2026-18738?: Medium severity. CVSS v3 base score is 4.7 out of 10.