CVE-2021-41270

NameCVE-2021-41270
DescriptionSymfony/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 `@`.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
NVD severitymedium

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
symfony (PTS)stretch (security), stretch2.8.7+dfsg-1.3+deb9u3fixed
buster, buster (security)3.4.22+dfsg-2+deb10u1fixed
bullseye4.4.19+dfsg-2vulnerable
bookworm, sid5.4.2+dfsg-3fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
symfonysourcestretch(not affected)
symfonysourcebuster(not affected)
symfonysource(unstable)4.4.19+dfsg-3

Notes

[bullseye] - symfony <no-dsa> (Minor issue; can be fixed via point release)
[buster] - symfony <not-affected> (Vulnerable code and support for csv_escape_formulas introduced in 4.1)
[stretch] - symfony <not-affected> (Vulnerable code and support for csv_escape_formulas introduced in 4.1)
https://github.com/symfony/symfony/security/advisories/GHSA-2xhg-w2g5-w95x
https://github.com/symfony/symfony/commit/3da6f2d45e7536ccb2a26f52fbaf340917e208a8 (v4.4.35)
https://symfony.com/blog/cve-2021-41270-prevent-csv-injection-via-formulas

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