GHSA-x67x-vg9m-65c3 is a critical-severity (CVSS 9.8) Buffer Overflow vulnerability in base64. O3 Security confirms whether GHSA-x67x-vg9m-65c3 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Integer overflow in base64
Real-World Exposure
base64Real-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
Affected versions of this crate suffered from an integer overflow bug when
calculating the size of a buffer to use when encoding base64 using the
encode_config_buf and encode_config functions. If the input string
was large, this would cause a buffer to be allocated that was too small.
Since this function writes to the buffer using unsafe code, it would
allow an attacker to write beyond the buffer, causing memory corruption
and possibly the execution of arbitrary code.
This flaw was corrected by using checked arithmetic to calculate the size of the buffer.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | base64 | all versions | 0.5.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for base64. 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 base64 to 0.5.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-x67x-vg9m-65c3 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-x67x-vg9m-65c3 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-x67x-vg9m-65c3. 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-x67x-vg9m-65c3 in your dependencies?
O3 detects GHSA-x67x-vg9m-65c3 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.