Vulnerability in github.com/sylabs/singularity (CVE-2020-13846)

Summary

Vulnerability in github.com/sylabs/singularity (CVE-2020-13846). Data can be tampered with by attackers. Exploitable via WARNING. Mitigation: upgrade to 3.6.0 or later.

Original description

The description as published by the source.

Impact

The --all / -a option to singularity verify returns success even when some objects in a SIF container are not signed, or cannot be verified.

The SIF objects that are not verified are reported in WARNING log messages, but a Container Verified message and exit code of 0 are returned.

Workflows that verify a container using --all / -a and use the exit code as an indicator of success are vulnerable to running SIF containers that have unsigned, or modified, objects that may be exploited to introduce malicious behavior.

$ singularity verify -a image.sif 
WARNING: Missing signature for SIF descriptor 2 (JSON.Generic)
WARNING: Missing signature for SIF descriptor 3 (FS)
Container is signed by 1 key(s):

Verifying partition: Def.FILE:
12045C8C0B1004D058DE4BEDA20C27EE7FF7BA84
[LOCAL]   Unit Test 
[OK]      Data integrity verified

INFO:    Container verified: image.sif

$ echo $?
0

Patches

Singularity 3.6.0 has a new implementation of sign/verify that fixes this issue.

All users are advised to upgrade to 3.6.0. Note that Singularity 3.6.0 uses a new signature format that is necessarily incompatible with Singularity < 3.6.0 - e.g. Singularity 3.5.3 cannot verify containers signed by 3.6.0.

Version 3.6.0 includes a --legacy-insecure flag for the singularity verify command, that will perform verification of the older, and insecure, legacy signatures for compatibility with existing containers. This does not guarantee that containers have not…

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-2020-13846 has been found in github.com/sylabs/singularity.
Attackers can target a specific entry point like WARNING over the network to misuse the product.
Data can be tampered with by attackers.
What to do: upgrade github.com/sylabs/singularity to 3.6.0 or later.
If unsure, ask your IT team or search "github.com/sylabs/singularity CVE-2020-13846" on the vendor's site.

CVE-2020-13846 (github.com/sylabs/singularity)
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: WARNING
Patched: 3.6.0 — apply immediately
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 (unclassified) exists in github.com/sylabs/singularity. Attackers reach the vulnerable code path via WARNING without authentication.

📍 Affected scope

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

🔥 Severity

Severity: ?. Data can be tampered with by attackers.

🔧 How to fix

Update to 3.6.0.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 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 patch patch
```
Upgrade github.com/sylabs/singularity to 3.6.0
```
ステージング環境で 3.6.0 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。
3
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":"3.5.0"},{"fixed":"3.6.0"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

Ubuntu UBUNTU-CVE-2020-13846 singularity-container