GHSA-2xhg-w2g5-w95x
MEDIUMCSV Injection in symfony/serializer
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
symfony/serializer🐘symfony/serializer🐘symfony/symfony🐘symfony/symfonyReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Description
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 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 for branch 4.4.
Credits
We would like to thank Jake Barwell for reporting the issue and Jérémy Derussé for fixing the issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | symfony/serializer | ≥ 5.0.0&&< 5.3.12 | 5.3.12 |
| 🐘Packagist | symfony/serializer | ≥ 4.1.0&&< 4.4.35 | 4.4.35 |
| 🐘Packagist | symfony/symfony | ≥ 4.1.0&&< 4.4.35 | 4.4.35 |
| 🐘Packagist | symfony/symfony | ≥ 5.0.0&&< 5.3.12 | 5.3.12 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/serializer. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update symfony/serializer to 5.3.12 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2xhg-w2g5-w95x is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-2xhg-w2g5-w95x is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-2xhg-w2g5-w95x. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-2xhg-w2g5-w95x in your dependencies?
O3 detects GHSA-2xhg-w2g5-w95x across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.