Execution Control List (ECL) Is Insecure in Singularity

Exploitation

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

CVSS

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

EPSS

• CVE-2020-13845: 0.52% estimated exploitation activity in the next 30 days; percentile 44.04 (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.

Impact The Singularity Execution Control List (ECL) allows system administrators to set up a policy that defines rules about what signature(s) must be (or must not be) present on a SIF container image for it to be permitted to run. In Singularity 3.x versions below 3.6.0, the following issues allow the ECL to be bypassed by a malicious user: Image integrity is not validated when an ECL policy is enforced. The fingerprint required by the ECL is compared against the signature object descriptor(s) in the SIF file, rather than to a cryptographically validated signature. Thus, it is trivial to craft an arbitrary payload which will be permitted to run, even if the attacker does not have access to the private key associated with the fingerprint(s) configured in the ECL. Patches These issues are addressed in Singularity 3.6.0. 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.…

Published by the source

20 Dec 2021, 18:24 UTC

Last modified by the source

20 Jan 2023, 22:02 UTC

Source last checked

26 Oct 2026, 14:54 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-pmfr-63c2-jr5c

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# Patch Next advisory brief: CVE-2020-13845

Advisory: Execution Control List (ECL) Is Insecure in Singularity
IDs: CVE-2020-13845, GHSA-pmfr-63c2-jr5c
Record: https://patchnext.com/advisories/cve-2020-13845 (revision 1, source checked 26 Oct 2026, 14:54 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/sylabs/singularity 3.6.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/sylabs/singularity: affected >= 3.0.0, < 3.6.0; fixed in 3.6.0

## Suggested inspection (read-only)
- Go github.com/sylabs/singularity: check the installed version with your package manager.

## 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 github.com/sylabs/singularity.
- 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-pmfr-63c2-jr5c (GitHub-reviewed advisory GHSA-pmfr-63c2-jr5c lists affected ranges: Go github.com/sylabs/singularity >=3.0.0 <3.6.0)

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