CVE-2026-91969

# Unbounded CSV row cardinality permits API process termination ## Summary The authenticated v2 CSV migration route caps upload bytes but not parsed row cardinality. It reads every record into a [][]string and then materializes a full task object for every row before insertion. Two million one-cell rows fit in a roughly 4 MB multipart request yet exhaust a 512 MiB API process. ## Impact and affected scope - **Type:** Resource Exhaustion Csv Import - **Affected component:** POST /api/v2/migration/csv/migrate - **Preconditions:** An ordinary authenticated user supplies a multipart CSV containing a very large number of tiny records plus a valid mapping configuration. - **Verified revision:** `349cd5adbcc831ef08b08e6c9c6d627603c39606` on 28 August 2026 - **Affected release range:** `= 2.5.0`; broader historical range not established and maintainer confirmation requested A low-privileged remote user can terminate the API process and deny service to all users with a request far below the configured upload-byte limit. ## Technical details csv.Reader.ReadAll retains every row, after which convertToVikunja allocates a task structure for each row; the existing upload-byte cap does not constrain this cardinality amplification. Attack path: Authenticate, upload two million one-cell records to the synchronous CSV migrate route with a valid ignore mapping, and exhaust process memory while parsing and materializing rows. Relevant code: - `pkg/routes/api/v2/migration_csv.go:96` - `pkg/routes/api/v2/migration_csv.go:164` - `pkg/modules/migration/csv/csv.go:281` - `pkg/modules/migration/csv/csv.go:298` - `pkg/modules/migration/csv/csv.go:590` - `pkg/modules/migration/csv/csv.go:605` - `pkg/modules/migration/csv/csv.go:627` - `pkg/modules/migration/csv/csv.go:643` - `pkg/modules/migration/csv/csv.go:655` ## Reproduction Run this only against an authorized disposable environment. The complete verified minimum file set is reproduced below. It starts the isolated target, runs