CVE-2026-18738: Software Security Vulnerability Vulnerability

MODERATE
Advisory Identifier: GHSA-ghrv-q878-w45x
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CVSS 4.7
CWE-1236
Published
Advisory Summary

CVE-2026-18738 is a MODERATE (CVSS 4.7) security vulnerability vulnerability (CWE-1236: Improper Neutralization of Formula Elements in a CSV File) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product saves user-provided information into a comma-separated value (csv) file, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as a command when the file is opened by a spreadsheet product.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-18738 at a Glance

CVE Identifier CVE-2026-18738
GHSA Identifier GHSA-ghrv-q878-w45x
Severity MODERATE
CVSS v3.1 Base Score 4.7
CWE Classification CWE-1236: Improper Neutralization of Formula Elements in a CSV File
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 4.7

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Changed (S:C)
Confidentiality Low (C:L)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-18738

To remediate this vulnerability, upgrade all affected Software dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-18738, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

Analyze the terminal output to locate any version of Software in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The mvn dependency:tree command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-1236: Improper Neutralization of Formula Elements in a CSV File, where the product saves user-provided information into a comma-separated value (csv) file, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as a command when the file is opened by a spreadsheet product. In Software, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

References

NVD — CVE-2026-18738 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-18738
Software Source Repository REPOSITORY
https://github.com/shlinkio/shlink
Software Source Repository REPOSITORY
https://github.com/theopaid/CSV-formula-injection-in-visit-exports-shlink-
www.vulncheck.com/advisories/shlink-c... WEB
https://www.vulncheck.com/advisories/shlink-csv-formula-injection-via-visit-export-cli

Frequently Asked Questions

What is CVE-2026-18738?
CVE-2026-18738 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-1236: Improper Neutralization of Formula Elements in a CSV File.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-18738?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-18738?
CVE-2026-18738 has a CVSS v3.1 base score of 4.7 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N.
What CWE is associated with CVE-2026-18738?
CVE-2026-18738 is classified under CWE-1236: Improper Neutralization of Formula Elements in a CSV File (The product saves user-provided information into a Comma-Separated Value (CSV) file, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as a command when the file is opened by a spreadsheet product.).
How can I check Maven dependencies for CVE-2026-18738?
Run the dependency tree command: 'mvn dependency:tree'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-ghrv-q878-w45x",
  "modified" : "2026-08-03T21:31:38Z",
  "published" : "2026-08-03T21:31:38Z",
  "aliases" : [ "CVE-2026-18738" ],
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-18738"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/shlinkio/shlink"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/theopaid/CSV-formula-injection-in-visit-exports-shlink-"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/shlink-csv-formula-injection-via-visit-export-cli"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1236" ],
    "severity" : "MODERATE",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-08-03T21:16:38Z"
  }
}