CVE-2026-40036

Unfurl < 2026.04 - Denial of Service via Unbounded zlib Decompression

HIGH
7.5
CVSS Score
Published: April 8, 2026 at 09:35 PM UTC
Updated: October 8, 2026 at 04:17 PM UTC
2 products affected across 2 vendorsUnfurlUnfurl

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Severity
HIGH7.5
Exploit prediction
EPSS 0.5%
SSVC
PoC

Description

dfir-unfurl through 20250810 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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 2026.04*
Affected range stops below 2026.04, so it looks safe — our inference, not a vendor statement
0 ≤ v < 2026.040
Affected range stops below 2026.04, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHVulnCheck
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-400CWE-770CWE-409

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