CVE-2025-64508
HIGHBugsink vulnerable to unauthenticated remote DoS via crafted Brotli input
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
bugsinkReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Bugsink is a self-hosted error tracking tool. In versions prior to 2.0.5, brotli "bombs" (highly compressed brotli streams, such as many zeros) can be sent to the server. Since the server will attempt to decompress these streams before applying various maximums, this can lead to exhaustion of the available memory and thus a Denial of Service. This can be done if the DSN is known, which it is in many common setups (JavaScript, Mobile Apps). The issue is patched in Bugsink version 2.0.5. The vulnerability is similar to, but distinct from, another brotli-related problem in Bugsink, GHSA-rrx3-2x4g-mq2h/CVE-2025-64509.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | bugsink | all versions | 2.0.5 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for bugsink. 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 bugsink to 2.0.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-64508 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 CVE-2025-64508 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 CVE-2025-64508. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2025-64508 in your dependencies?
O3 detects CVE-2025-64508 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.