cosign: Improper Verification of Cryptographic Signature
CVE-2022-35929 is a critical-severity improper verification of cryptographic signature vulnerability in cosign from Sigstore, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected cosign versions: < 1.10.1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.68% chance of exploitation within 30 days, higher than 53% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of cosign 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.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
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
- NoneNo account or login is needed.
- 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:N/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 | 9.8 | Critical | NVD |
Official description
cosign is a container signing and verification utility. In versions prior to 1.10.1 cosign can report a false positive if any attestation exists. `cosign verify-attestation` used with the `--type` flag will report a false positive verification 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"). This can happen when signing with a standard keypair and with "keyless" signing with Fulcio. This vulnerability can be reproduced with the `distroless.dev/static@sha256:dd7614b5a12bc4d617b223c588b4e0c833402b8f4991fb5702ea83afad1986e2` image. This image has a `vuln` attestation but not an `spdx` attestation. However, if you run `cosign verify-attestation --type=spdx` on this image, it incorrectly succeeds. This issue has been addressed in version 1.10.1 of cosign. Users are advised to upgrade. There are no known workarounds for this issue.
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: poc, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- github.com/sigstore/cosign/security/advisories/GHSA-vjxv-45g9-9296Exploit, Third Party Advisory
Patches and release notes
- github.com/sigstore/cosign/commit/c5fda01a8ff33ca981f45a9f13e7fb6bd2080b94Exploit, Third Party Advisory
Other vulnerabilities in cosign
- 7.5 High severity
Recent Improper Verification of Cryptographic Signature vulnerabilities
- 8.8 High 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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