Vulnerability in github.com/sylabs/singularity (CVE-2020-25040)

Summary

Vulnerability in github.com/sylabs/singularity (CVE-2020-25040). Successful exploitation can lead to full system takeover. Exploitable via TMPDIR. Mitigation: upgrade to 3.6.3 or later.

Original description

The description as published by the source.

Impact

Insecure permissions on temporary directories used in explicit and implicit container build operations.

When a Singularity command that results in a container build operation is executed, it is possible for a user with access to the system to read the contents of the image during the build. Additionally, if the image contains a world-writable file or directory, it is possible for a user to inject arbitrary content into the running build, which in certain circumstances may enable arbitrary code execution during the build and/or when the built container is run.

Patches

This issue is addressed in Singularity 3.6.3.

All users are advised to upgrade to 3.6.3.

Workarounds

The issue is mitigated if TMPDIR is set to a location that is only accessible to the user, as any subdirectories directly under TMPDIR cannot then be accessed by others. However, this is difficult to enforce so it is not recommended to rely on this as a mitigation.

For more information

General questions about the impact of the advisory / changes made in the 3.6.0 release can be asked in the:

Any sensitive security concerns should be directed to: security@sylabs.io

See our Security Policy here: https://sylabs.io/security-policy

Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2020-25040 has been found in github.com/sylabs/singularity.
Attackers can target a specific entry point like TMPDIR over the network to misuse the product.
Successful exploitation can lead to full system takeover.
What to do: upgrade github.com/sylabs/singularity to 3.6.3 or later.
If unsure, ask your IT team or search "github.com/sylabs/singularity CVE-2020-25040" on the vendor's site.

CVE-2020-25040 (github.com/sylabs/singularity) — CWE-668
Attack vector: remote (network-reachable) / no user interaction
Attack surface: TMPDIR
Patched: 3.6.3 — apply immediately
Workaround: The issue is mitigated if TMPDIR is set to a location that is only accessible to the user, as any subdirectories directly under TMPDIR cannot then be accessed by others.
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-668) exists in github.com/sylabs/singularity. Attackers reach the vulnerable code path via TMPDIR.

📍 Affected scope

Check the vendor advisory for the affected versions of github.com/sylabs/singularity. Attack surface: TMPDIR.

🔥 Severity

Severity: ?. Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to 3.6.3.

🛡️ Workaround

Workaround: The issue is mitigated if TMPDIR is set to a location that is only accessible to the user, as any subdirectories directly under TMPDIR cannot then be accessed by others.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'github.com/sylabs/singularity' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

1
Identify exposure identify
```
grep -r 'github.com/sylabs/singularity' . | grep -v node_modules
```
リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で github.com/sylabs/singularity を grep し、稼働しているサービス・バージョンを把握する。
2
Apply temporary workaround mitigate
```
The issue is mitigated if `TMPDIR` is set to a location that is only accessible to the user, as any subdirectories directly under `TMPDIR` cannot then be accessed by others.
```
パッチが適用されるまでの応急処置として、The issue is mitigated if TMPDIR is set to a location that is only accessible to the user, as any subdirectories directly under TMPDIR cannot then be accessed by others. を実施。回避策の副作用 (機能低下) を確認した上で。
3
Apply patch patch
```
Upgrade github.com/sylabs/singularity to 3.6.3
```
ステージング環境で 3.6.3 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
4
Post-deployment verification verify
```
Confirm patched version is live in production
```
パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

Go github.com/sylabs/singularity

[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"3.6.3"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

Ubuntu UBUNTU-CVE-2020-25040 singularity-container