Vulnerability CVE-2021-41270

Vulnerability Name:

CVE-2021-41270 (CCN-214072)

Assigned:

2021-11-24

Published:

2021-11-24

Updated:

2021-12-15

Summary:

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 `@`.

CVSS v3 Severity:

6.5 Medium (CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N)
5.7 Medium (Temporal CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C)

Exploitability Metrics:	Attack Vector (AV): Network Attack Complexity (AC): Low Privileges Required (PR): Low User Interaction (UI): None
Scope:	Scope (S): Unchanged
Impact Metrics:	Confidentiality (C): High Integrity (I): None Availibility (A): None

7.8 High (CCN CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H)
6.8 Medium (CCN Temporal CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C)

Exploitability Metrics:	Attack Vector (AV): Local Attack Complexity (AC): Low Privileges Required (PR): None User Interaction (UI): Required
Scope:	Scope (S): Unchanged
Impact Metrics:	Confidentiality (C): High Integrity (I): High Availibility (A): High

CVSS v2 Severity:

4.0 Medium (CVSS v2 Vector: AV:N/AC:L/Au:S/C:P/I:N/A:N)

Exploitability Metrics:	Access Vector (AV): Network Access Complexity (AC): Low Authentication (Au): Single_Instance
Impact Metrics:	Confidentiality (C): Partial Integrity (I): None Availibility (A): None

6.8 Medium (CCN CVSS v2 Vector: AV:L/AC:L/Au:S/C:C/I:C/A:C)

Exploitability Metrics:	Access Vector (AV): Local Access Complexity (AC): Low Athentication (Au): Single_Instance
Impact Metrics:	Confidentiality (C): Complete Integrity (I): Complete Availibility (A): Complete