CVE-2021-23654Network attack vector

Spreadsheet command execution via unneutralized CSV formulas

Published Nov 26, 2021 · Updated Sep 16, 2024

CSV formula injection in Wentao Han html2csv 0.1.3 and earlier allows remote attackers to embed spreadsheet commands via crafted HTML. Converter.convert_to_list copies stripped table-cell strings into rows, and convert_to_csv passes them directly to csv.writer.writerow without neutralizing formula prefixes. Execution requires a downstream spreadsheet to open the generated CSV and interpret an attacker-controlled cell as a formula; otherwise, the output remains a malicious CSV payload.

CVSS severity5.6
Medium
EPSS probability1.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

CSV formula injection in Wentao Han html2csv 0.1.3 and earlier allows remote attackers to embed spreadsheet commands via crafted HTML. Converter.convert_to_list copies stripped table-cell strings into rows, and convert_to_csv passes them directly to csv.writer.writerow without neutralizing formula prefixes. Execution requires a downstream spreadsheet to open the generated CSV and interpret an attacker-controlled cell as a formula; otherwise, the output remains a malicious CSV payload.

The record

CVE
CVE-2021-23654
Published
Nov 26, 2021
Updated
Sep 16, 2024
Vendor
Wentao Han
Product
html2csv
Classifications
CWE-1236, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 26, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record 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=0 <unspecified

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Wentao Han · html2csvversion=0 <unspecified

Published CVSS scores

6.3GitHub Advisory DatabaseCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N
9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
5.6SnykCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
7.5NVDAV:N/AC:L/Au:N/C:P/I:P/A:P

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 exploitUnconfirmed

Weakness, pattern, technique

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

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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