Banks: Path traversal in DirectoryPromptRegistry.set() allows arbitrary file write outside the registry root

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

6.0 · CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-71492: 0.47% estimated exploitation activity in the next 30 days; percentile 41.03 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary DirectoryPromptRegistry.set() interpolates the attacker-controllable Prompt.name into a Path expression with no canonicalization. An application that derives the prompt name from request data lets a caller write attacker-controlled bytes outside the configured registry directory. Details src/banks/registries/directory.py:44 Two failure modes: 1. Relative traversal. name="../victim/foo" resolves to <registry/../victim/foo.0.jinja — outside the configured root. 2. Absolute-path bypass. pathlib documents that Path("/a") / Path("/b") returns Path("/b"). So name="/abs/path" discards the registry root entirely; the registry is never consulted. The poisoned name is then persisted to index.json, so the out-of-root path keeps reconstructing on later load() calls (directory.py:135-141). With overwrite=True, existing files at the target path are replaced. Proof of Concept Output (verified on banks==2.4.2): testsandboxbaseline.py <img width="793" height="149" alt="Screenshot 2026-05-10…

Published by the source

2 Sep 2026, 14:38 UTC

Last modified by the source

2 Sep 2026, 14:38 UTC

Source last checked

26 Oct 2026, 13:51 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-x8wg-4xgc-vr54

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# Patch Next advisory brief: CVE-2026-71492

Advisory: Banks: Path traversal in `DirectoryPromptRegistry.set()` allows arbitrary file write outside the registry root
IDs: CVE-2026-71492, GHSA-x8wg-4xgc-vr54
Record: https://patchnext.com/advisories/cve-2026-71492 (revision 1, source checked 26 Oct 2026, 13:51 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: banks 2.4.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI banks: affected < 2.4.5; fixed in 2.4.5

## Suggested inspection (read-only)
- `python -m pip show banks`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on banks.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-x8wg-4xgc-vr54 (GitHub-reviewed advisory GHSA-x8wg-4xgc-vr54 lists affected ranges: PyPI banks >=0 <2.4.5)

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