Nextflow EUVD-2026-78578

Exploitation requires all of the following to be true simultaneously: (1) the victim has run nextflow auth login at least once on a Nextflow version between 25.09.2-edge and 26.04.1, generating a seqera-auth.config file; (2) the attacker holds a local shell account on the same multi-user POSIX host; (3) the victim's home directory is world-traversable (execute bit set for others - mode 711 or 755, which is the default on most Linux distributions and HPC systems). Exploitation is blocked when: the home directory is mode 700 (not world-traversable, making the file unreachable even though it is world-readable); the victim exclusively uses the TOWER_ACCESS_TOKEN environment variable and never invokes nextflow auth login; or the system is single-user or a headless CI runner where the interactive auth flow is never invoked. The file permission flaw does not affect the Seqera Platform service itself - it is purely a local credential-theft primitive on the client host.

The NVD CVSS 3.1 vector AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N (score 5.5) accurately characterizes the threat: local access is mandatory, no privilege escalation is needed beyond a standard shell account, exploitation is low-complexity, and the sole impact is complete confidentiality loss of the stored credential. No EPSS score was supplied in the available intelligence data, so probabilistic exploitation likelihood cannot be quantified from this analysis. The vulnerability is not listed in the CISA KEV catalog, and no public exploit code has been identified at time of analysis - these two signals suggest opportunistic mass exploitation is not currently occurring. However, the practical risk in HPC and shared research infrastructure is meaningfully higher than the raw score implies: home directories on Linux HPC clusters are commonly world-traversable (mode 755 or 711 by default), Nextflow's primary user base operates on exactly these systems, and exploitation requires zero tooling beyond standard shell access. The 'Privilege Escalation' tag is appropriate - a low-privileged local user effectively acquires Seqera Platform access scoped to the victim's token. The flaw is irrelevant on single-user systems and headless CI runners, which materially narrows real-world exposure.

A low-privileged user on a shared bioinformatics HPC login node - where dozens of researchers share a single system to submit Nextflow jobs - notices that a colleague's home directory is world-traversable. The attacker runs cat ~victim/.nextflow/seqera-auth.config and immediately obtains a valid Seqera Platform bearer token requiring no special tools or privilege. Using the token in an HTTP Authorization header, the attacker authenticates to Seqera Platform as the victim, gaining access to proprietary genomics pipelines, datasets, compute quotas, and organizational resources within the token's scope.