CVE-2026-40036

Summary

Unfurl before 2026.04 contains an unbounded zlib decompression vulnerability in parse_compressed.py that allows remote attackers to cause denial of service. Attackers can submit highly compressed payloads via URL parameters to the /json/visjs endpoint that expand to gigabytes, exhausting server memory and crashing the service.

Affected Software

Weaknesses

• CWE-770: Allocation of Resources Without Limits or Throttling
• CWE-409: Improper Handling of Highly Compressed Data (Data Amplification)

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: poc
  • Automatable: yes
  • Technical Impact: partial

References

• https://github.com/obsidianforensics/unfurl/security/advisories/GHSA-h5qv-qjv4-pc5m
• https://github.com/obsidianforensics/unfurl/releases/tag/v2026.04
• https://www.vulncheck.com/advisories/dfir-unfurl-denial-of-service-via-unbounded-zlib-decompression

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