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GHSA-9vc9-4jv3-rf86

HighCVSS 8.5 / 10
Published Jun 10, 2026·Last modified Jun 10, 2026
Affected Components(0)

No affected components available

Description

Affected: @hulumi/policies < 1.4.0Fixed in: 1.4.0Severity: High — CWE-284 (Improper Access Control)

Summary

HULUMI-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.

The 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.

Impact

Consumers 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.

Patches

Upgrade 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.

Workarounds

None — the exemption itself is the mechanism, so the value-binding check is the only fix.

Resources

  • PR #178 (Cluster B); decoy-sibling regression cases in packages/policies/tests/hulumi-hardening-pack.test.ts. Supersedes PR #175, which had addressed the value-binding half but on a stale base.
Risk Scores
Base Score
8.5

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability.

Threat Intelligence
5.8

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.26%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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