Vulnerability-Lookup

CVE-2026-18738 (GCVE-0-2026-18738)

Vulnerability from cvelistv5 – Published: 2026-08-03 20:53 – Updated: 2026-08-04 15:05

Title

Shlink CSV Formula Injection via Visit Export CLI

Summary

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

5.1 (Medium)


                        
                          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

4.7 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-04 14:28 UTC

CWE

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

Assigner

VulnCheck

References

3 references

URL	Tags
https://github.com/theopaid/CSV-formula-injection…	vendor-advisory
https://github.com/shlinkio/shlink	product
https://www.vulncheck.com/advisories/shlink-csv-f…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version
shlinkio	Shlink	Affected: 5.0.0 , ≤ 5.1.5 (git)

Date Public

2026-08-03 00:00

Credits

Theodosis Paidakis

Show details on NVD website

JSON

To clipboard

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  "containers": {
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      {
        "metrics": [
          {
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                "id": "CVE-2026-18738",
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}

GHSA-GHRV-Q878-W45X

Vulnerability from github – Published: 2026-08-03 21:31 – Updated: 2026-08-03 21:31

Details

Severity

4.7 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N

5.1 (Medium)


                  
                    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

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-18738"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1236"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-03T21:16:38Z",
    "severity": "MODERATE"
  },
  "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\u0027s client machine when the exported CSV file is opened in a spreadsheet application that evaluates formulas.",
  "id": "GHSA-ghrv-q878-w45x",
  "modified": "2026-08-03T21:31:38Z",
  "published": "2026-08-03T21:31:38Z",
  "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"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N",
      "type": "CVSS_V3"
    },
    {
      "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",
      "type": "CVSS_V4"
    }
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

CVE-2026-18738 (GCVE-0-2026-18738)

GHSA-GHRV-Q878-W45X

Tags

Sightings

Nomenclature