GHSA-cqvm-j2r2-hwpg is a medium-severity (CVSS 5.9) Improper Input Validation vulnerability in russh. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether GHSA-cqvm-j2r2-hwpg is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
russh may use insecure Diffie-Hellman keys
Exploitation Status
No confirmed exploitation observed yet
- 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-cqvm-j2r2-hwpg.
Real-World Exposure
russh🦀russhReal-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
Diffie-Hellman key validation is insufficient, which can lead to insecure shared secrets and therefore breaks confidentiality.
Details
Russh does not validate Diffie-Hellman keys.
It accepts received DH public keys $e$ where $e<0$, $e=1$, or $e \geq p-1$ from a misbehaving peer annd successfully performs key exchange.
This is a violation of RFC 4253, section 8 and RFC 8268, section 4, which state that:
DH Public Key values MUST be checked and both conditions:
- $1 < e < p-1$
- $1 < f < p-1$
MUST be true. Values not within these bounds MUST NOT be sent or accepted by either side. If either one of these conditions is violated, then the key exchange fails.
For example, a DH client public key $e=1$ would mean that the shared secret that the server calculates is always $K = e^y \mod{p} = 1^y \mod{p} = 1$. In other cases, an insecure order-2 subgroup may be used.
Also, the code does not look like it ensures that the generated secret key $y$ is in the valid interval $0 < y < q$ (or, if russh is the client, that the secret key $x$ satisfies $1 < x < q$):
https://github.com/warp-tech/russh/blob/master/russh/src/kex/dh/groups.rs#L72-L76
For example, rng.gen_biguint() might return a number consisting of zeroes, so that $y = 0$.
The public key is not validated either: https://github.com/warp-tech/russh/blob/master/russh/src/kex/dh/groups.rs#L78-L81
Impact
Due to the issues in the DH key generation, I think any connection that uses Diffie-Hellman key exchange is affected. Connections between a russh client and server or those of a russh peer with some other misbehaving peer are most likely to be problematic. These may vulnerable to eavesdropping.
Most other implementations reject such keys, so this is mainly an interoperability issue in such a case.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | russh | all versions | 0.36.2 |
| 🦀crates.io | russh | ≥ 0.37.0&&< 0.37.1 | 0.37.1 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for russh. 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 russh to 0.36.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-cqvm-j2r2-hwpg 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-cqvm-j2r2-hwpg 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-cqvm-j2r2-hwpg. 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-cqvm-j2r2-hwpg in your dependencies?
O3 detects GHSA-cqvm-j2r2-hwpg across crates.io dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.