GHSA-r78f-4q2q-hvv4 — ursa
MEDIUMGHSA-r78f-4q2q-hvv4 is a medium-severity (CVSS 6.5) Broken Cryptographic Algorithm vulnerability in ursa. No vendor fix is recorded yet; mitigation options are listed below.
CL-Signatures Revocation Scheme in Ursa has flaws that allow a holder to demonstrate non-revocation of a revoked credential
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- 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 GHSA-r78f-4q2q-hvv4.
EPSS Exploitation Probability
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.
How urgent is this, really
GHSA-r78f-4q2q-hvv4 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
ursa🦀anoncreds-clsignaturesReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
Summary
The revocation schema that is part of the Ursa CL-Signatures implementations has a flaw that could impact the privacy guarantees defined by the AnonCreds verifiable credential model, allowing a malicious holder of a revoked credential to generate a valid Non-Revocation Proof for that credential as part of an AnonCreds presentation.
Details
The revocation schema that is part of the Ursa CL-Signatures implementation has a flaw that could impact the privacy guarantees defined by the AnonCreds verifiable credential model, allowing a malicious holder of a revoked credential to generate a valid Non-Revocation Proof for that credential as part of an AnonCreds presentation.
The flaw exists in all CL-Signature versions published from the Hyperledger Ursa repository to the Ursa Rust Crate, and are fixed in all versions published from the Hyperledger AnonCreds CL-Signatures repository to the AnonCreds CL-Signatures Rust Crate.
To exploit the flaw, a holder must update their wallet (agent) software, replacing the Hyperledger Ursa or AnonCreds CL-Signatures library that generates the proof of non-revocation. This may involve, for example, altering an iOS or Android application published in the respective app stores. A mitigation for this flaw is to use the application attestation capabilities (such as the Android "SafetyNet Attestation API") offered by the app store vendors to (for example) "help determine whether your servers are interacting with your genuine app running on a genuine Android device."
The problem is created in the generation of a revocation registry, prior to issuing any credentials. As such, to eliminate the impact of the flaw, the issued credentials must be re-issued based on a correct revocation registry, generated from a correct implementation, such as Hyperledger AnonCreds CL-Signatures.
Impact
The potential impact is as follows:
- A verifier may verify a credential from a holder as being "not revoked" when in fact, the holder's credential has been revoked.
Mitigation
Upgrade libraries/applications using the Ursa Rust Crate to any version of the AnonCreds CL-Signatures Rust Crate. If your application has issued revocable credentials, once the Issuer library has been upgraded, new revocation registries must be created, and credentials issued from revocation registries created with the the flawed software must be revoked and reissued.
A verifier can detect if a holder presents a flawed revocable credential.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | ursa | all versions | No fix |
| 🦀crates.io | anoncreds-clsignatures | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ursa, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
No patched version of ursa has shipped for GHSA-r78f-4q2q-hvv4 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-r78f-4q2q-hvv4 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-r78f-4q2q-hvv4. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-r78f-4q2q-hvv4 in your dependencies?
O3 Security finds GHSA-r78f-4q2q-hvv4 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.