Summary
"Verify All" Returns Success Despite Validation Failures in Singularity
Workarounds
If you are unable to update to 3.6.0 ensure that you do not rely on the return code of singularity verify --all / -a as an indicator of trust in a container.
Note that other issues in the sign/verify implementation in Singularity < 3.6.0 allow additional means to introduce malicious behavior to a signed container.
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: [email protected]
See our Security Policy here: https://sylabs.io/security-policy
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 <[email protected]>
[OK] Data integrity verified
INFO: Container verified: image.sif
$ echo $?
0
CVE-2020-13846 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.6.0); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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See it in your environmentNew to Kodem? Get a demo →Remediation advice
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 been modified since signing, due to other issues in the legacy signature format.
Frequently Asked Questions
- What is CVE-2020-13846? CVE-2020-13846 is a high-severity security vulnerability in github.com/sylabs/singularity (go), affecting versions >= 3.5.0, < 3.6.0. It is fixed in 3.6.0.
- How severe is CVE-2020-13846? CVE-2020-13846 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/sylabs/singularity are affected by CVE-2020-13846? github.com/sylabs/singularity (go) versions >= 3.5.0, < 3.6.0 is affected.
- Is there a fix for CVE-2020-13846? Yes. CVE-2020-13846 is fixed in 3.6.0. Upgrade to this version or later.
- Is CVE-2020-13846 exploitable, and should I be worried? Whether CVE-2020-13846 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2020-13846 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2020-13846? Upgrade
github.com/sylabs/singularityto 3.6.0 or later.