GHSA-x9w5-v3q2-3rhw
HIGHbrowserify-sign upper bound check issue in `dsaVerify` leads to a signature forgery attack
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.
Blast Radius
browserify-signReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
Summary
An upper bound check issue in dsaVerify function allows an attacker to construct signatures that can be successfully verified by any public key, thus leading to a signature forgery attack.
Details
In dsaVerify function, it checks whether the value of the signature is legal by calling function checkValue, namely, whether r and s are both in the interval [1, q - 1]. However, the second line of the checkValue function wrongly checks the upper bound of the passed parameters, since the value of b.cmp(q) can only be 0, 1 and -1, and it can never be greater than q.
In this way, although the values of s cannot be 0, an attacker can achieve the same effect as zero by setting its value to q, and then send (r, s) = (1, q) to pass the verification of any public key.
Impact
All places in this project that involve DSA verification of user-input signatures will be affected by this vulnerability.
Fix PR:
Since the temporary private fork was deleted, here's a webarchive of the PR discussion and diff pages: PR webarchive.zip
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | browserify-sign | ≥ 2.6.0&&< 4.2.2 | 4.2.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for browserify-sign. 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 browserify-sign to 4.2.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-x9w5-v3q2-3rhw 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-x9w5-v3q2-3rhw 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-x9w5-v3q2-3rhw. 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-x9w5-v3q2-3rhw in your dependencies?
O3 detects GHSA-x9w5-v3q2-3rhw across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.