Nextflow is a DSL for data-driven computational pipelines. From 25.09.2-edge until 25.10.6 and 26.04.3, nextflow auth login writes Seqera Platform OIDC bearer tokens to ${NXF_HOME:-~/.nextflow}/seqera-auth.config through AuthCommandImpl.writeConfig in plugins/nf-tower/src/main/io/seqera/tower/plugin/auth/AuthCommandImpl.groovy without setting restrictive file permissions, allowing the default umask 022 to create the file with mode 0644. On a multi-user POSIX host, a local user who can traverse the victim's home directory can read seqera-auth.config and impersonate the victim against Seqera Platform within the token's scope. Single-user systems and headless CI runners that do not use the interactive login flow are not affected. This issue is fixed in 25.10.6 and 26.04.3.