CVE-2026-6621

Exploitation

Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.

SSVC decision

• ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
• AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
• Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.34% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 26.4% of scored records. A rank, not a probability.

NVD base score

5.5 (CVSS v4.0), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

NVD analysis status

Deferred. NVD last modified this record on 2026-06-17.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2026-04-20 08:30Z4 MO AGO

Last updated

2026-04-20 15:33Z4 MO AGO

Reserved

2026-04-19

Assigning CNA

VulDB

Record state

PUBLISHED

Severity

Medium (CVSS 6.9)

CNA CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P

Weaknesses

• CWE-94Improper Control of Generation of Code ('Code Injection')Base
• CWE-1321Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')Variant

Data version

5.2

Document digest

531153c8648e11dafacd80c7faa615ec2853f292d3a4f5abc8deab8147d31003

• vuldb.comVDB-358256 | 1024bit extend-deep index.js prototype pollutionhttps://vuldb.com/vuln/358256vdb-entrytechnical-description
• vuldb.comVDB-358256 | CTI Indicators (IOB, IOC, TTP, IOA)https://vuldb.com/vuln/358256/ctisignaturepermissions-required
• vuldb.comSubmit #792387 | 1024bit extend-deep 0.1.6 Prototype Pollutionhttps://vuldb.com/submit/792387third-party-advisory
• github.comhttps://github.com/sudo-secure/security-research/blob/main/extend-deep/prototype-pollution/PoC.mdexploit