vulnerability / NVI-00001829 / Revision 2
CSV Injection in symfony/serializer
OSV carries this publisher advisory for symfony/serializer, symfony/serializer, symfony/symfony, symfony/symfony. This is an aggregated source copy; consult the original publisher and compare update dates.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
1.400%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.72501. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
symfony/serializer
source listedECOSYSTEM: introduced 5.0.0; fixed 5.3.12
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 issu
symfony/serializer
source listedECOSYSTEM: introduced 4.1.0; fixed 4.4.35
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 issu
symfony/symfony
source listedECOSYSTEM: introduced 4.1.0; fixed 4.4.35
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 issu
symfony/symfony
source listedECOSYSTEM: introduced 5.0.0; fixed 5.3.12
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 issu
03 / Response
What to do next
- vendor patch
The original advisory lists fixed boundaries 5.3.12 for symfony/serializer. Confirm the publisher’s latest guidance.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database via OSV
- vendor patch
The original advisory lists fixed boundaries 4.4.35 for symfony/serializer. Confirm the publisher’s latest guidance.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database via OSV
- vendor patch
The original advisory lists fixed boundaries 4.4.35 for symfony/symfony. Confirm the publisher’s latest guidance.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database via OSV
- vendor patch
The original advisory lists fixed boundaries 5.3.12 for symfony/symfony. Confirm the publisher’s latest guidance.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database via OSV
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-2xhg-w2g5-w95x ↗
GitHub Advisory Database via OSV · vendor advisory
Observed . GitHub-origin advisory, CC-BY-4.0; OSV is an aggregate copy, not independent corroboration.
- CVE-2021-41270 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 2 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.