Home/CVE/Unfurl before 2026.04 contains an unbounded zlib decompression vulnerability in parse_compressed.py that allows remote
CVE

CVE-2026-40036

Unfurl before 2026.04 contains an unbounded zlib decompression vulnerability in parse_compressed.py that allows remote

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.

HIGH · CVSS 7.5 EPSS 0.00211
Act now
  • Public exploit or PoC is available
  • SSVC automatable: yes - attacks can be scripted at scale
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬡

Weakness Classification

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

Affected Products & Versions

1
ryandfir unfurl< 2026.04
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
PyPI dfir-unfurl HIGH fixed in 20260405
⚠

Public Exploits & PoCs

1
pocgithub.com · GHSA-h5qv-qjv4-pc5mgithub.com
▣

Scoring & Timeline

7.5
HIGH · CVSS v3.1 · disclosure@vulncheck.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD08 Apr 2026 · 10:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC triage · cisa-vulnrichment
Exploitation
poc
Automatable
yes
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
🔗

References & Sources

2
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/obsidianforensics/unfurl/releases/tag/v2026.04Release Notes
https://www.vulncheck.com/advisories/dfir-unfurl-denial-of-service-via-unbounded-zlib-decompressionThird Party Advisory
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