Thumbor has path traversal via post-validation URL decoding bypass in file_loader
Priority HIGH 77CWE-22Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-22 and the CVSS impact.
Summary
Thumbor is an open-source photo thumbnail service by globo.com. Prior to 7.8.0, file_loader decodes percent-encoded path segments after its root-boundary validation, allowing traversal outside FILE_LOADER_ROOT_PATH through watermark or frame filter input. This issue is fixed in 7.8.0.
Why it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00522 44th percentileScored 2026-11-07
Fix Fixed thumbor (thumbor): 7.8.0thumbor (PyPI): 7.8.0
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- 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 |
|---|---|---|---|---|---|
| thumbor | thumbor | before 7.8.0 | 7.8.0 | Patch available | CNA |
| — | thumbor (PyPI) | before 7.8.0 | 7.8.0 | Patch available | GHSA-cj54-hpcc-gj6h |
- thumbor Vendorthumbor Affected before 7.8.0 Fixed in 7.8.0 Patch available CNA
- thumbor (PyPI) Vendor— Affected before 7.8.0 Fixed in 7.8.0 Patch available GHSA-cj54-hpcc-gj6h
Remediation
- Fix · CNA thumbor (thumbor) Fixed in 7.8.0
- Fix · GHSA-cj54-hpcc-gj6h thumbor (PyPI) Fixed in 7.8.0 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-53502
- 2026-10-03 Alias added: GHSA-cj54-hpcc-gj6h
References
More thumbor vulnerabilities
- TI-2026-38575 Thumbor treats ALLOWED_SOURCES string patterns as unescaped regex, allowing hostname bypass via wildcard dot CVSS 3.1HIGH 8.2
- TI-2026-38580 Thumbor proportion filter allows unbounded post-transform resize leading to remote DoS CVSS 3.1HIGH 7.5
- TI-2026-38579 Thumbor has Regex Denial of Service (ReDoS) in `convolution` filter CVSS 3.1HIGH 7.5
- TI-2026-38578 Thumbor convolution filter allows divide-by-zero in C extension leading to remote DoS CVSS 3.1HIGH 7.5
- TI-2026-38576 Thumbor has HMAC validation bypass via multiple .replace() calls when removing URL signature CVSS 3.1HIGH 8.2
Sources
- CVE-2026-53502 · CVE Program
- CVE-2026-53502 · NVD
- FIRST EPSS
- GHSA-cj54-hpcc-gj6h · 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