How severe is CVE-2023-25656?

CVE-2023-25656 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2023-25656?

CVE-2023-25656 affects the following packages: github.com/notaryproject/notation-go (Go). Ecosystems affected: Go.

How do I fix CVE-2023-25656?

Update github.com/notaryproject/notation-go to 1.0.0-rc.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-25656 is resolved across your whole dependency graph.

How do I detect CVE-2023-25656 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/notaryproject/notation-go, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2023-25656 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2023-25656 actively exploited in the wild?

No public exploit code has been indexed for CVE-2023-25656 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 CVE-2023-25656?

CVE-2023-25656 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 38th 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.

What type of vulnerability is CVE-2023-25656?

CVE-2023-25656 is classified as CWE-770 (CWE-770). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2023-25656 published, and has it been updated?

CVE-2023-25656 was published on February 20, 2023 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹

🐹 Go

Not in CISA KEV

HIGH severity

CVE-2023-25656 — notation-go

HIGHFix: notaryproject/notation-go#275

CVE-2023-25656 is a high-severity (CVSS 7.5) CWE-770 vulnerability in github.com/notaryproject/notation-go. A fix is available for github.com/notaryproject/notation-go — see the affected versions and patch details below.

notation-go has excessive memory allocation on verification

Also known asGHSA-87x9-7grx-m28vGO-2023-1589

Published

Feb 20, 2023

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2023-25656.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs38th percentile — riskier than 38% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

🐹github.com/notaryproject/notation-go

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

notation-go users will find their application using excessive memory when verifying signatures and the application will be finally killed, and thus availability is impacted.

Patches

The problem has been patched in the release v1.0.0-rc.3. Users should upgrade their notation-go packages to v1.0.0-rc.3 or above.

Workarounds

Users can review their own trust policy file and check if the identity string contains =#. Meanwhile, users should only put trusted certificates in their trust stores referenced by their own trust policy files, and make sure the authenticity validation is set to enforce

Credits

The notation-go project would like to thank Adam Korczynski (@AdamKorcz) for responsibly disclosing this issue during a security fuzzing audit sponsored by CNCF and Shiwei Zhang (@shizhMSFT) for root cause analysis and detailed vulnerability report.

References

Resource exhaustion attacks

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/notaryproject/notation-go`	all versions	1.0.0-rc.3`go get github.com/notaryproject/notation-go@v1.0.0-rc.3`

Affected Products

1 product · 3 configurations

Application

notation-gonotaryproject

3 versions

0.7.00.8.00.9.0

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/notaryproject/notation-go, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/notaryproject/notation-go to 1.0.0-rc.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-25656 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

### Impact `notation-go` users will find their application using excessive memory when verifying signatures and the application will be finally killed, and thus availability is impacted. ### Patches The problem has been patched in the release [v1.0.0-rc.3](https://github.com/notaryproject/notation-go/releases/tag/v1.0.0-rc.3). Users should upgrade their `notation-go` packages to `v1.0.0-rc.3` or above. ### Workarounds Users can review their own trust policy file and check if the identity string contains `=#`. Meanwhile, users should only put trusted certificates in their trust stores refe