GHSA-hw43-fcmm-3m5g is a high-severity (CVSS 7.5) Broken Cryptographic Algorithm vulnerability in gov.nsa.emissary:emissary. A fix is available for gov.nsa.emissary:emissary — see the affected versions and patch details below.
Emissary May Use a Broken or Risky Cryptographic Algorithm
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for GHSA-hw43-fcmm-3m5g.
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-hw43-fcmm-3m5g 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 377,333 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
gov.nsa.emissary:emissaryReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
Summary
The ChecksumCalculator class within allows for hashing and checksum generation, but it includes or defaults to algorithms that are no longer recommended for secure cryptographic use cases (e.g., SHA-1, CRC32, and SSDEEP). These algorithms, while possibly valid for certain non-security-critical tasks, can expose users to security risks if used in scenarios where strong cryptographic guarantees are required.
Requirement from NIST
Requirement from NIST regarding SHA1
Federal agencies should use SHA-2 or SHA-3 as an alternative to SHA-1. Further guidance will be available soon. Send questions on the transition to [email protected].
https://www.nist.gov/news-events/news/2022/12/nist-retires-sha-1-cryptographic-algorithm
Mitigation and Fix
Make it clear to developers and users that the ChecksumCalculator is specific to the "Known File Filter" (KFF) document similarity feature and is not intended to suggest or endorse global use as a cryptographically secure hashing or checksum mechanism.
While these specific default insecure algorithms can not be updated without violating the intended use-case, it can be clearly documented and prevented using better access modifiers in the ChecksumCalculator class.
Details
Within ChecksumCalculator.java, the following points raise potential security concerns:
SHA-1: SHA-1 has been widely deprecated for cryptographic purposes due to known collision attacks. The constructor defaults to "SHA-1" if no specific algorithm is provided. CRC32: CRC32 is a simple checksum mechanism, not a cryptographic hash function. It is unsuitable for security-critical integrity checks since it can be easily manipulated or collided. SSDEEP (Fuzzy Hashing): SSDEEP is a context-specific tool used for similarity matching and may not be a secure cryptographic function for authentication or tamper detection. There is no apparent mechanism to prevent developers from using these weaker algorithms in security-sensitive contexts. Users of emissary who rely on ChecksumCalculator for strong security guarantees (e.g., data integrity or authentication) may be misled into assuming these algorithms provide adequate protection.
PoC
Code could be found https://github.com/NationalSecurityAgency/emissary/blob/main/src/main/java/emissary/kff/ChecksumCalculator.java
Impact
Impact Weakened Security Posture: Applications integrating Emissary may inadvertently use these algorithms in a way that could be exploited (e.g., collisions in SHA-1, trivial collisions in CRC32). Misleading Assurance: Developers might assume Emissary’s recommended defaults are secure for cryptographic validation, which can result in insecure implementations. Potential for Collision Attacks: Attackers could craft inputs that yield the same SHA-1 hash or manipulate CRC32 sums, thus bypassing naive integrity checks. Because this project is produced under the NSA umbrella, users may have an inflated trust in its security posture, potentially leading them to rely on these algorithms in high-security environments without recognizing the associated risks.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | gov.nsa.emissary:emissary | all versions | 8.24.0gov.nsa.emissary:emissary:8.24.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for gov.nsa.emissary:emissary, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update gov.nsa.emissary:emissary to 8.24.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-hw43-fcmm-3m5g 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-hw43-fcmm-3m5g can be triaged on real exposure rather than presence alone.
Tailored to GHSA-hw43-fcmm-3m5g. 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-hw43-fcmm-3m5g in your dependencies?
O3 Security finds GHSA-hw43-fcmm-3m5g across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.