Vulnerability in Sensiolabs Symfony
CVE-2021-41270
Symfony/Serializer handles serializing and deserializing data structures for Symfony, a PHP framework for web and console applications and a set of reusable PHP components. Symfony versions 4.1.0 before 4.4.35 and versions 5.0.0 before 5.3.12 are vulnerable to CSV injection, also known as formula injection. In Symfony 4.1, maintainers added the opt-in `csv_escape_formulas` option in the `CsvEncoder`, to prefix all cells starting with `=`, `+`, `-` or `@` with a tab `\t`. Since then, OWASP added 2 chars in that list: Tab (0x09) and Carriage return (0x0D). This makes the previous prefix char (Tab `\t`) part of the vulnerable characters, and OWASP suggests using the single quote `'` for prefixing the value. Starting with versions 4.4.34 and 5.3.12, Symfony now follows the OWASP recommendations and uses the single quote `'` to prefix formulas and add the prefix to cells starting by `\t`, `\r` as well as `=`, `+`, `-` and `@`.
EPSS: 0.014 (68.8th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.
Affected products
- Sensiolabs Symfony
- Symfony — versions >= 4.1.0, < 4.4.35, >= 5.0.0, < 5.3.12
- Fedoraproject Fedora — versions 34, 35
Weakness classification (CWE)
Public proof-of-concept exploits
References
- security-advisories@github.com (Patch, Third Party Advisory, x_refsource_MISC)
- security-advisories@github.com (Third Party Advisory, x_refsource_MISC, Release Notes)
- security-advisories@github.com (x_refsource_CONFIRM, Patch, Third Party Advisory)
- security-advisories@github.com (Patch, Third Party Advisory, x_refsource_MISC)
- security-advisories@github.com (x_refsource_FEDORA, vendor-advisory)
- security-advisories@github.com (x_refsource_FEDORA, vendor-advisory)
Frequently asked questions
- What is CVE-2021-41270?
- CVE-2021-41270 is a medium-severity vulnerability in Sensiolabs Symfony, classified under Improper Neutralization of Formula Elements in a CSV File. CVSS score: 6.5/10. Published 2021-11-24.
- How severe is CVE-2021-41270?
- Medium severity. CVSS v3 base score is 6.5 out of 10.
- Is CVE-2021-41270 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.