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
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
@finos/git-proxynpmDescription
Summary
An attacker can craft a malicious Git packfile to exploit the PACK signature detection in the parsePush.ts. By embedding a misleading PACK signature within commit content and carefully constructing the packet structure, the attacker can trick the parser into treating invalid or unintended data as the packfile. Potentially, this would allow bypassing approval or hiding commits.
Details
The affected version of parsePush.ts attempts to locate the Git PACK file by looking for the last occurrence of the string "PACK" in the incoming push payload:
const packStart = buffer.lastIndexOf('PACK');
This assumes that any "PACK" string near the end of the push is the beginning of the actual binary Git packfile. However, Git objects (commits, blobs, etc.) can contain arbitrary content (including the word PACK) in binary or non-compressed blobs.
An attacker could abuse this by:
- Crafting a custom packfile using low-level Git tools or by manually forging one
- Placing the string "PACK" inside a commit body or a binary file blob that appears after the real PACK start in the stream.
The parser then ignores the actual push and treats the binary blob/commit body as the PACK file. The actual push contents may violate existing push policies.
PoC
- Make a commit on any branch (example:
test-branch) containing the string "PACK" - Manually generate a custom packfile with both branches using
git pack-objectsor a low-level library/custom script: a) Add the string "PACK" after the real packfile's PACK header in the binary stream - Push using a custom client/raw protocol injection
Impact
Attackers with push access can hide commits from scanning/approval and make changes that bypass policies, potentially inserting unwanted/malicious code into a GitProxy protected repository.
The vulnerability impacts all users or organizations relying on GitProxy to enforce policies and prevent unapproved changes. It requires no elevated privileges beyond regular push access, and no extra user interaction, however, it does require a considerable amount of technical skill and intentional effort to accomplish.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @finos/git-proxy | all versions | 1.19.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @finos/git-proxy. 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 @finos/git-proxy to 1.19.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xxmh-rf63-qwjv 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-xxmh-rf63-qwjv 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-xxmh-rf63-qwjv. 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-xxmh-rf63-qwjv in your dependencies?
O3 detects GHSA-xxmh-rf63-qwjv across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.