policy-controller: Improper Verification of Cryptographic Signature
CVE-2022-35930 is a high-severity improper verification of cryptographic signature vulnerability in policy-controller from Sigstore, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected policy-controller versions: < 0.2.1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.7% chance of exploitation within 30 days, higher than 54% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of policy-controller you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Sigstore | policy-controller | < 0.2.1 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.1 | High | CNA (github.com) |
| CVSS 3.1 | 8.8 | High | NVD |
Official description
PolicyController is a utility used to enforce supply chain policy in Kubernetes clusters. In versions prior to 0.2.1 PolicyController will report a false positive, resulting in an admission when it should not be admitted when there is at least one attestation with a valid signature and there are NO attestations of the type being verified (--type defaults to "custom"). An example image that can be used to test this is `ghcr.io/distroless/static@sha256:dd7614b5a12bc4d617b223c588b4e0c833402b8f4991fb5702ea83afad1986e2`. Users should upgrade to version 0.2.1 to resolve this issue. There are no workarounds for users unable to upgrade.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Verification of Cryptographic Signature
The product does not verify, or incorrectly verifies, the cryptographic signature for data.
More Improper Verification of Cryptographic Signature vulnerabilities (CWE-347)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- github.com/sigstore/policy-controller/security/advisories/GHSA-739f-hw6h-7wq8Third Party Advisory
Patches and release notes
- github.com/sigstore/policy-controller/commit/e852af36fb7d42678b21d7e97503c25bd1fd05c8Third Party Advisory
- github.com/sigstore/policy-controller/releases/tag/v0.2.1Third Party Advisory
Recent Improper Verification of Cryptographic Signature vulnerabilities
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.5 High severity
- 9.8 Critical severity
- 9.8 Critical severity
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