Strands Agents: Local Privilege Escalation via Symlink Attack in Default Session File Storage

Exploitation

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

CVSS

7.1 · CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary The `FileSessionManager` defaults to storing session data in `/tmp/strands/sessions/` (a world-writable directory) using predictable file paths and a write pattern (`open(path + ".tmp", "w")` → `os.replace()`) that follows symbolic links. A local attacker can exploit this to overwrite arbitrary files or inject malicious session data for persistent prompt injection.

Vulnerability Details Component: `strands-py/src/strands/session/file_session_manager.py` Root Cause: 1. Default storage directory is `tempfile.gettempdir() + "/strands/sessions/"` (line 58) — resolves to `/tmp/strands/sessions/` on Linux/macOS 2. The `_write_file()` method (lines 116-123) writes to a predictable `.tmp` path without symlink protection: ```python tmp = f"{path}.tmp" with open(tmp, "w", encoding="utf-8", newline="\n") as f: json.dump(data, f, indent=2, ensure_ascii=False) os.replace(tmp, path) ``` 3. `open()` follows symlinks — a pre-placed symlink at the `.tmp` path causes writes to an…

Published by the source

27 Oct 2026, 15:34 UTC

Last modified by the source

27 Oct 2026, 15:47 UTC

Source last checked

28 Oct 2026, 06:10 UTC

1. Revision 2 · amended · 28 Oct 2026

   Amended from osv record GHSA-3w55-933p-8pv5

2. Revision 1 · created · 27 Oct 2026

   Published from ghsa record GHSA-3w55-933p-8pv5

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: GHSA-3w55-933p-8pv5

Advisory: Strands Agents: Local Privilege Escalation via Symlink Attack in Default Session File Storage
IDs: GHSA-3w55-933p-8pv5
Record: https://patchnext.com/advisories/ghsa-3w55-933p-8pv5 (revision 2, source checked 28 Oct 2026, 06:10 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: strands-agents 1.48.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI strands-agents: affected < 1.48.0; fixed in 1.48.0

## Suggested inspection (read-only)
- `python -m pip show strands-agents`: 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 strands-agents.
- 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://osv.dev/vulnerability/GHSA-3w55-933p-8pv5 (OSV record GHSA-3w55-933p-8pv5 lists affected ranges: PyPI strands-agents >=0 <1.48.0 (fixed))
- Verified: https://github.com/advisories/GHSA-3w55-933p-8pv5 (GitHub-reviewed advisory GHSA-3w55-933p-8pv5 lists affected ranges: PyPI strands-agents >=0 <1.48.0)

Commands are suggestions: review each one before running it.