{"id":"UBUNTU-CVE-2021-32635","details":"Singularity is an open source container platform. In verions 3.7.2 and 3.7.3, Dde to incorrect use of a default URL, `singularity` action commands (`run`/`shell`/`exec`) specifying a container using a `library://` URI will always attempt to retrieve the container from the default remote endpoint (`cloud.sylabs.io`) rather than the configured remote endpoint. An attacker may be able to push a malicious container to the default remote endpoint with a URI that is identical to the URI used by a victim with a non-default remote endpoint, thus executing the malicious container. Only action commands (`run`/`shell`/`exec`) against `library://` URIs are affected. Other commands such as `pull` / `push` respect the configured remote endpoint. The vulnerability is patched in Singularity version 3.7.4. Two possible workarounds exist: Users can only interact with the default remote endpoint, or an installation can have an execution control list configured to restrict execution to containers signed with specific secure keys.","modified":"2026-05-20T16:04:58.584420791Z","published":"2021-05-28T21:15:00Z","upstream":["CVE-2021-32635"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2021-32635"},{"type":"REPORT","url":"https://github.com/hpcng/singularity/security/advisories/GHSA-jq42-hfch-42f3"},{"type":"REPORT","url":"https://github.com/sylabs/singularity/security/advisories/GHSA-5mv9-q7fq-9394"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2021-32635"}],"affected":[{"package":{"name":"singularity-container","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/singularity-container?arch=source&distro=esm-apps%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.3.1-2","2.3.2-1","2.4.1-1","2.4.2-2","2.4.2-3","2.4.2-4","2.4.2-4ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_version":"2.4.2-4ubuntu0.1~esm1","binary_name":"singularity-container"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-32635.json"}},{"package":{"name":"singularity-container","ecosystem":"Ubuntu:Pro:24.04:LTS","purl":"pkg:deb/ubuntu/singularity-container?arch=source&distro=esm-apps%2Fnoble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.1.1+ds2-1","4.1.1+ds2-1build1","4.1.1+ds2-1ubuntu0.1","4.1.1+ds2-1ubuntu0.2","4.1.1+ds2-1ubuntu0.2+esm1","4.1.1+ds2-1ubuntu0.3","4.1.1+ds2-1ubuntu0.3+esm1","4.1.1+ds2-1ubuntu0.3+esm2"],"ecosystem_specific":{"binaries":[{"binary_name":"golang-github-sylabs-singularity-dev","binary_version":"4.1.1+ds2-1ubuntu0.3+esm2"},{"binary_version":"4.1.1+ds2-1ubuntu0.3+esm2","binary_name":"singularity-container"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-32635.json"}},{"package":{"name":"singularity-container","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/singularity-container?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.1.5+ds4-1"],"ecosystem_specific":{"binaries":[{"binary_version":"4.1.5+ds4-1","binary_name":"golang-github-sylabs-singularity-dev"},{"binary_version":"4.1.5+ds4-1","binary_name":"singularity-container"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-32635.json"}},{"package":{"name":"singularity-container","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/singularity-container?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.1.5+ds4-1"],"ecosystem_specific":{"binaries":[{"binary_version":"4.1.5+ds4-1","binary_name":"golang-github-sylabs-singularity-dev"},{"binary_version":"4.1.5+ds4-1","binary_name":"singularity-container"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-32635.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L"},{"type":"Ubuntu","score":"medium"}]}