{"id":"CVE-2026-48034","aliases":["GHSA-9vc9-4jv3-rf86"],"url":"https://o3.security/vulnerability/CVE-2026-48034","summary":"HULUMI-H5 bypass via decoy sibling resources targeting a different bucket","details":"**Affected:** `@hulumi/policies` `< 1.4.0` — **Fixed in:** `1.4.0` — **Severity:** High — **CWE-284 (Improper Access Control)**\n\n#### Summary\n\nHULUMI-H1 forbids raw `aws:s3:Bucket` outside of Hulumi's `SecureBucket` component, with one exemption: a raw bucket that's a child of a `SecureBucket` is allowed because the component is responsible for the hardening. HULUMI-H5 is the defence-in-depth check that closes the H1 exemption — for any raw bucket claiming it, H5 verifies the five hardening sibling resources a real `SecureBucket` always emits (public-access block, SSE-KMS, ownership controls, versioning, TLS-only bucket policy) are actually present.\n\nThe bug: H5 only checked the siblings' _types_. It never verified that those siblings actually applied to the bucket being exempted. A consumer (or compromised PR) could pair an unhardened raw bucket with five hardening sibling resources whose `bucket` property pointed at a _completely different_ bucket, and H5 would report no violation while the actual bucket shipped with zero hardened defaults.\n\n#### Impact\n\nConsumers using `HulumiHardeningPack` could ship a raw S3 bucket with no public-access block, no SSE-KMS, no ownership controls, no versioning, and no TLS-only bucket policy — while the policy pack reported the stack as compliant.\n\n#### Patches\n\nUpgrade to `@hulumi/policies@1.4.0`. The H5 sibling check now requires both (a) the sibling to share the same parent `SecureBucket` instance via the anchored URN helper from GHSA-2, AND (b) the sibling's `bucket` property — or, for the bucket policy, its `Resource` ARN list — to reference the exempted bucket explicitly. Five decoy siblings pointing at a different bucket no longer count.\n\n#### Workarounds\n\nNone — the exemption itself is the mechanism, so the value-binding check is the only fix.\n\n#### Resources\n\n- [PR #178](https://github.com/kerberosmansour/hulumi/pull/178) (Cluster B); decoy-sibling regression cases in `packages/policies/tests/hulumi-hardening-pack.test.ts`. Supersedes [PR #175](https://github.com/kerberosmansour/hulumi/pull/175), which had addressed the value-binding half but on a stale base.","published":"2026-07-24T18:38:53.735Z","modified":"2026-10-21T02:58:17.330939711Z","cvss":null,"epss":{"score":0.00258,"percentile":0.17304,"asOf":"2026-09-02"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"@hulumi/policies","fixedVersion":"1.4.0"}],"fix":{"url":"https://github.com/kerberosmansour/hulumi/pull/175","label":"kerberosmansour/hulumi#175"},"references":[{"type":"WEB","url":"https://github.com/kerberosmansour/hulumi/releases/tag/v1.4.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48034.json"},{"type":"ADVISORY","url":"https://github.com/kerberosmansour/hulumi/security/advisories/GHSA-9vc9-4jv3-rf86"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48034"},{"type":"FIX","url":"https://github.com/kerberosmansour/hulumi/pull/175"},{"type":"FIX","url":"https://github.com/kerberosmansour/hulumi/pull/178"},{"type":"PACKAGE","url":"https://github.com/kerberosmansour/hulumi"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:58:17.330939711Z"}}