Bugsink vulnerable to unauthenticated remote DoS via crafted Brotli input
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-770.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| bugsink | bugsink | before 2.0.5 | 2.0.5 | Patch available | CNA |
| — | bugsink (PyPI) | before 2.0.5 | 2.0.5 | Patch available | GHSA-fc2v-vcwj-269v |
- bugsink Vendorbugsink Affected before 2.0.5 Fixed in 2.0.5 Patch available CNA
- bugsink (PyPI) Vendor— Affected before 2.0.5 Fixed in 2.0.5 Patch available GHSA-fc2v-vcwj-269v
Remediation
- Fix · CNA bugsink (bugsink) Fixed in 2.0.5
- Fix · GHSA-fc2v-vcwj-269v bugsink (PyPI) Fixed in 2.0.5 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2025-64508
- 2026-10-03 Alias added: GHSA-fc2v-vcwj-269v
References
Other 9
- https://github.com/bugsink/bugsink/security/advisories/GHSA-fc2v-vcwj-269v
- https://github.com/google/brotli/issues/1327
- https://github.com/google/brotli/issues/1375
- https://github.com/bugsink/bugsink/pull/266
- https://github.com/google/brotli/pull/1234
- https://github.com/bugsink/bugsink/commit/3f65544aab3ad5303d97009136640de97b0676a5
- https://github.com/google/brotli/commit/67d78bc41db1a0d03f2e763497748f2f69946627
- https://github.com/google/brotli/releases/tag/v1.2.0
- https://github.com/bugsink/bugsink
More bugsink vulnerabilities
- TI-2026-22000 Bugsink is vulnerable to Stored XSS via Pygments fallback in stacktrace rendering CVSS 3.1CRITICAL 9.3
- TI-2025-39901 Bugsink vulnerable to unauthenticated remote DoS via crafted Brotli input (via CPU) CVSS 3.1HIGH 7.5
- TI-2025-34236 Bugsink is vulnerable to Path Traversal attacks via event_id in ingestion CVSS 4.0HIGH 7.2
- TI-2026-28977 Bugsink affected by authenticated arbitrary file write in artifactbundle/assemble CVSS 3.1HIGH 7.1
- TI-2026-38922 Bugsink: DOS using large numbers of event tags CVSS 3.1MEDIUM 4.3
- TI-2026-32436 Bugsink: SSRF bypass in `validate_webhook_url` CVSS 3.1MEDIUM 4.3
Sources
- CVE-2025-64508 · CVE Program
- CVE-2025-64508 · NVD
- FIRST EPSS
- GHSA-fc2v-vcwj-269v · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences