{"id":"CVE-2026-100838","aliases":["GHSA-rh99-wc69-c255","GO-2026-5624"],"url":"https://o3.security/vulnerability/CVE-2026-100838","summary":"Contrast before 1.19.1 CopyFile Policy Symlink Subversion","details":"### Impact\n\nThe [Kata agent policies](https://docs.edgeless.systems/contrast/architecture/components/policies) generated by the Contrast CLI had an issue in the `CopyFile` verification, which allowed arbitrary writes to the guest root filesytem. A malicious process on the host with the capability to connect to the Kata agent VSOCK could connect to the agent and issue a series of `CopyFile` requests to overwrite security-critical files or trick the workload into disclosing sensitive data, which effectively amounts to a full guest takeover.\n\n### Patches\n\nThis issue has been patched in Contrast v1.19.1.\n\nNote that this fix does not change the fact that host-provided content is generally not trustworthy, as documented.\n\n### Workarounds\n\nIf upgrading is not possible, users can implement the fix in rego and pass it to `contrast generate --policy`. The rego-only fix is a bit trickier than the patch, because the data to check is binary. See the references for details.\n\n### Resources\n\n* Upstream GHSA: https://github.com/kata-containers/kata-containers/security/advisories/GHSA-q49m-57vm-c8cc\n* Alternative policy-only fix: https://gist.github.com/burgerdev/304dd0ab0fff1665b7c27e18a30cf96e","published":"2026-09-27T01:28:35.498Z","modified":"2026-09-28T03:48:30.954855648Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Go","name":"github.com/edgelesssys/contrast","fixedVersion":"1.19.1"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/100xxx/CVE-2026-100838.json"},{"type":"ADVISORY","url":"https://github.com/edgelesssys/contrast/security/advisories/GHSA-rh99-wc69-c255"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-100838"},{"type":"ADVISORY","url":"https://www.vulncheck.com/advisories/contrast-before-1.19.1-copyfile-policy-symlink-subversion"},{"type":"WEB","url":"https://github.com/kata-containers/kata-containers/security/advisories/GHSA-q49m-57vm-c8cc"},{"type":"WEB","url":"https://gist.github.com/burgerdev/304dd0ab0fff1665b7c27e18a30cf96e"},{"type":"PACKAGE","url":"https://github.com/edgelesssys/contrast"},{"type":"WEB","url":"https://github.com/edgelesssys/contrast/releases/tag/v1.19.1"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-28T03:48:30.954855648Z"}}