🛡️ CVE-2021-41270 — symfony

🟡 CVSS 5.0 — Medium ✅ No Known Exploit OSV
5.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

CSV Injection in symfony/serializer

Description

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CSV Injection, also known as Formula Injection, occurs when websites embed untrusted input inside CSV files. When a spreadsheet program opens a CSV, any cell starting with = is interpreted by the software as a formula and could be abused by an attacker.

In Symfony 4.1, we've added the opt-in csv_escape_formulas option in CsvEncoder, to prefix all cells starting by =, +, - or @ by a tab \t.

Since then, OWASP added 2 chars in that list:

  • Tab (0x09)
  • Carriage return (0x0D)

This makes our previous prefix char (Tab \t) part of the vulnerable characters, and [OWASP suggests](https://owasp.org/www-community/attacks/CSV_Injection) using the single quote ' for prefixing the value.

Resolution

----------

Symfony now follows the OWASP recommendations and use the single quote ' to prefix formulas and adds the prefix to cells starting by \t, \r as well as =, +, - and @.

The patch for this issue is available [here](https://github.com/symfony/symfony/commit/3da6f2d45e7536ccb2a26f52fbaf340917e208a8) for branch 4.4.

Credits

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We would like to thank Jake Barwell for reporting the issue and Jérémy Derussé for fixing the issue.

Affected software

CVE-2021-41270 is recorded against 3 packages.

  • symfony
  • symfony/serializer (from 4.1.0 up to 4.4.35)
  • symfony/symfony (from 5.0.0 up to 5.3.12)

Timeline and source

Published on 6 March 2024. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

github.com (Web)
github.com (Web)
github.com (Web)
github.com (Web)
lists.fedoraproject.org (Web)
lists.fedoraproject.org (Web)

CVE-2021-41270 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity MEDIUM
CVSS Score 5.0
CVSS Vector N/A
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2024-03-06
Updated 2026-08-12
Modified 2024-03-06
Fix URL N/A

Affected Packages

Software From version Fixed in
symfony — —
symfony/serializer 4.1.0 4.4.35
symfony/symfony 5.0.0 5.3.12

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