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Response snapshot Oct 27, 2026, 16:01 UTC

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VulnerabilityGHSA-763v-5pjm-fx36

Strands Agents: Default FileSessionManager storage is world-readable on shared systems

There is a local confidentiality issue in the default `FileSessionManager` storage behavior. By default it writes session data under `/tmp/strands/sessions` and relies on the process umask for directory and file permissions.

At a glance

Exploited
Not known
Severity
Not scored yet
Chance of exploitation
Not estimated
Sources
1 source

What to do

GitHub lists first patched versions: strands-agents: 1.48.0. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-763v-5pjm-fx36 (opens a new tab)

What happened

There is a local confidentiality issue in the default `FileSessionManager` storage behavior. By default it writes session data under `/tmp/strands/sessions` and relies on the process umask for directory and file permissions. On systems using the common `umask 022`, the session directories are `0755` and JSON files are `0644`, so other local users can read persisted agent session data.

This matters on shared developer machines, CI hosts, notebooks, jump boxes, and multi-user GPU servers. Session storage is intended to persist conversation/history/state, so it can contain prompts, model output, tool inputs/outputs, intermediate state, and secrets that pass through the agent.

Relevant code: - `strands-py/src/strands/session/file_session_manager.py:58`: default storage path is `os.path.join(tempfile.gettempdir(), "strands/sessions")`. - `strands-py/src/strands/session/file_session_manager.py:118`: creates parent directories without a private mode. - `strands-py/src/strands/session/file_session_manager.py:121`: writes JSON files via normal `open(..., "w")`.

- `strands-py/src/strands/session/file_session_manager.py:131`: creates session directories without a private mode.

Continue reading

Local reproduction with `umask 022`:

```text default_storage_dir= /tmp/strands/sessions 0o755 /tmp/strands/sessions 0o755 /tmp/strands/sessions/session_codex_perm_poc 0o644 /tmp/strands/sessions/session_codex_perm_poc/session.json file_contains_secret= True ```

The fixture wrote a fake secret into the session dict to show that sensitive session fields are readable through the resulting file.

Suggested fixes: - Use a private per-user data directory by default rather than `/tmp`, or create `/tmp/strands` and descendants with `0700`. - Write session JSON atomically with `0600` permissions. - Consider refusing to use an existing default storage directory if it is not owned by the current user or is group/world accessible. - Document that callers should set `storage_dir` explicitly when they need shared storage.

This was reproduced on commit `dd7b41de38cb`.

Affected package ranges reported by GitHub: strands-agents: < 1.48.0

Related technology

Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-763v-5pjm-fx36 (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-763v-5pjm-fx36, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 27). Strands Agents: Default FileSessionManager storage is world-readable on shared systems. https://kevwire.com/record/GHSA-763v-5pjm-fx36

MLA

"Strands Agents: Default FileSessionManager storage is world-readable on shared systems." KEVWire, 27 Oct. 2026, kevwire.com/record/GHSA-763v-5pjm-fx36.

Chicago

KEVWire. "Strands Agents: Default FileSessionManager storage is world-readable on shared systems." Last modified October 27, 2026. https://kevwire.com/record/GHSA-763v-5pjm-fx36.

Evidence summary (plain text)

Strands Agents: Default FileSessionManager storage is world-readable on shared systems (Oct 27, 2026).
There is a local confidentiality issue in the default `FileSessionManager` storage behavior. By default it writes session data under `/tmp/strands/sessions` and relies on the process umask for directory and file permissions. On systems using the common `umask 022`, the session directories are `0755` and JSON files are `0644`, so other local users can read persisted agent session data.

This matters on shared developer machines, CI hosts, notebooks, jump boxes, and multi-user GPU servers. Session storage is intended to persist conversation/history/state, so it can contain prompts, model output, tool inputs/outputs, intermediate state, and secrets that pass through the agent.
Sources:
GitHub-reviewed advisory GHSA-763v-5pjm-fx36: https://github.com/advisories/GHSA-763v-5pjm-fx36
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc
Record ID: GHSA-763v-5pjm-fx36.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 27, 2026, 16:00 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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