How severe is GHSA-ccxc-vr6p-4858?

GHSA-ccxc-vr6p-4858 has a CVSS score of 3.3/10, rated LOW. Review your exposure and patch according to your risk tolerance.

Which packages are affected by GHSA-ccxc-vr6p-4858?

GHSA-ccxc-vr6p-4858 affects the following packages: github.com/sigstore/cosign (Go). Ecosystems affected: Go.

How do I fix GHSA-ccxc-vr6p-4858?

Update github.com/sigstore/cosign to 1.5.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-ccxc-vr6p-4858 is resolved across your whole dependency graph.

How do I detect GHSA-ccxc-vr6p-4858 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/sigstore/cosign. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-ccxc-vr6p-4858 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-ccxc-vr6p-4858?

O3 pinpoints whether GHSA-ccxc-vr6p-4858 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-ccxc-vr6p-4858 actively exploited in the wild?

No public exploit code has been indexed for GHSA-ccxc-vr6p-4858 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-ccxc-vr6p-4858?

GHSA-ccxc-vr6p-4858 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 6th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

When was GHSA-ccxc-vr6p-4858 published, and has it been updated?

GHSA-ccxc-vr6p-4858 was published on February 22, 2022 and was last updated on December 6, 2023. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹 Go

GHSA-ccxc-vr6p-4858

LOW

Improper Certificate Validation in Cosign

Also known asBIT-cosign-2022-23649CVE-2022-23649GO-2022-0326

Published

Feb 22, 2022

Updated

Dec 6, 2023

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk6th percentile+0.14%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

🐹github.com/sigstore/cosign

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Impact

Cosign can be manipulated to claim that an entry for a signature exists in the Rekor transparency log even if it doesn't. This requires the attacker to have pull and push permissions for the signature in OCI. This can happen with both standard signing with a keypair and "keyless signing" with Fulcio.

Signing with a keypair

To reproduce this vulnerability, create a keypair and sign an image. Don't store the signature in Rekor:

$ cosign generate-key-pair       
$ cosign sign --key cosign.key IMAGE

If an attacker has access to the signature in OCI, they can manipulate cosign into believing the entry was stored in Rekor even though it wasn't. To accomplish this, the attacker needs to:

Pull the signature image
Annotate the signature image with any valid Rekor bundle under the dev.sigstore.cosign/bundle annotation
Push the signature image back to OCI

Verification then prints out the following:

$ cosign verify [--key]  [IMAGE]

Verification for [IMAGE] --
The following checks were performed on each of these signatures:
  - The cosign claims were validated
  - Existence of the claims in the transparency log was verified offline
  - The signatures were verified against the specified public key
  - Any certificates were verified against the Fulcio roots.

[…]

The claim that Existence of the claims in the transparency log was verified offline is inaccurate since an entry for this image doesn't exist in the log. The claim that Any certificates were verified against the Fulcio roots. is technically correct but since there were no certificates that should be explicitly called out.

</details>

"Keyless signing" with an OIDC flow

To reproduce this vulnerability, sign the image with a Fulcio identity. Don't store the signature in Rekor:

$ COSIGN_EXPERIMENTAL=1 cosign sign IMAGE
[...]
IMAGE appears to be a private repository, please confirm uploading to the transparency log at "https://rekor.sigstore.dev" [Y/N]: n

Then, create a keypair and sign the image again. Store an entry for the signature in Rekor:

$ cosign generate-key-pair       
$ COSIGN_EXPERIMENTAL=1 cosign sign --key cosign.key IMAGE

Enter password for private key: IMAGE appears to be a private repository, please confirm uploading to the transparency log at "https://rekor.sigstore.dev" [Y/N]: y

If an attacker has access to the signature in OCI, they can manipulate cosign into believing the entry was stored in Rekor even though it wasn't. To accomplish this, the attacker needs to:

Pull the signature image
Copy the rekor bundle from the second signature into the first signature under the dev.sigstore.cosign/bundle annotation
Push the signature image back to OCI

Note: For this to work, both signatures must occur during the valid lifespan of the certificate (~20 minutes).

Verification then prints out the following:

$ cosign verify [--key]  [IMAGE]

Verification for [IMAGE] --
The following checks were performed on each of these signatures:
  - The cosign claims were validated
  - Existence of the claims in the transparency log was verified offline
  - The signatures were verified against the specified public key
  - Any certificates were verified against the Fulcio roots.

[…]

The claim that Existence of the claims in the transparency log was verified offline is inaccurate since an entry for this image doesn't exist in the log.

The claim that Any certificates were verified against the Fulcio roots. is technically correct but since there were no certificates that should be explicitly called out.

</details>

Patches

The vulnerability has been patched in v1.5.2 of cosign.

The signature in the signedEntryTimestamp provided by Rekor is now compared to the signature that is being verified. If these don't match, then an error is returned. If a valid bundle is copied to a different signature, verification should fail.

Cosign output now only informs the user that certificates were verified if a certificate was in fact verified.

Workarounds

The only workaround is upgrading.

For more information

If you have any questions or comments about this advisory:

Open an issue in cosign
Send us a message on Slack. Invite link here.

Thank you

Thank you to @mtrmac for finding and reporting this vulnerability.

Thank you to everyone who worked on fixing this:

@nsmith5
@znewman01
@dlorenc
@mattmoor
@priyawadhwa

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/sigstore/cosign`	all versions	1.5.2

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/sigstore/cosign. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/sigstore/cosign to 1.5.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-ccxc-vr6p-4858 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-ccxc-vr6p-4858 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-ccxc-vr6p-4858. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Impact Cosign can be manipulated to claim that an entry for a signature exists in the Rekor transparency log even if it doesn't. This requires the attacker to have pull and push permissions for the signature in OCI. This can happen with both standard signing with a keypair and "keyless signing" with Fulcio. #### Signing with a keypair <details> To reproduce this vulnerability, create a keypair and sign an image. Don't store the signature in Rekor: ``` $ cosign generate-key-pair $ cosign sign --key cosign.key IMAGE ``` If an attacker has access to the signature in OCI, they can

O3 Security · Impact-Aware SCA

Is GHSA-ccxc-vr6p-4858 in your dependencies?

O3 detects GHSA-ccxc-vr6p-4858 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works

GHSA-ccxc-vr6p-4858

EPSS Exploitation Probability

Blast Radius

Description

Impact

Signing with a keypair

"Keyless signing" with an OIDC flow

Patches

Workarounds

For more information

Thank you

Affected Packages

Detection & mitigation playbook

Detect

Fix

Workarounds

How O3 protects you

Frequently Asked Questions

Is GHSA-ccxc-vr6p-4858 in your dependencies?