CVE-2026-18738Public exploitNetwork attack vectorHinoki check available

Client-side formula evaluation via unescaped visit exports

Published Aug 3, 2026 · Updated Aug 3, 2026

CSV formula injection in Shlink 5.0.0 through 5.1.5 allows remote attackers to plant formulas in exported visit data. VisitsCommandUtils.php passes visitor-controlled user-agent, referer, and visited-URL values directly to league/csv without applying its EscapeFormula formatter. An administrator must export visits through the CLI and open the CSV in a formula-evaluating spreadsheet; the public proof shows formula parsing, not execution in any named spreadsheet.

CVSS severity5.1
Medium
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

CSV formula injection in Shlink 5.0.0 through 5.1.5 allows remote attackers to plant formulas in exported visit data. VisitsCommandUtils.php passes visitor-controlled user-agent, referer, and visited-URL values directly to league/csv without applying its EscapeFormula formatter. An administrator must export visits through the CLI and open the CSV in a formula-evaluating spreadsheet; the public proof shows formula parsing, not execution in any named spreadsheet.

The record

CVE
CVE-2026-18738
Published
Aug 3, 2026
Updated
Aug 3, 2026
Vendor
Shlink
Product
Shlink
Classifications
CWE-1236, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 3, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.0.0 <=5.1.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Shlink · Shlinkversion=5.0.0 <=5.1.5

Published CVSS scores

5.1VulnCheck CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
4.7VulnCheck CNACVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-1236Improper Neutralization of Formula Elements in a CSV File
T1204.002Malicious File

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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