CVE-2026-1526Network attack vector

Denial of service via decompression bomb

Published Mar 12, 2026 · Updated Mar 12, 2026

Resource exhaustion in affected Undici WebSocket clients allows remote attackers to crash Node.js processes via compressed server frames. PerMessageDeflate.decompress() retains every decompressed chunk and concatenates them without limiting the expanded data size. Exposure requires permessage-deflate negotiation with an attacker-controlled WebSocket server; the bounded consequence is process memory exhaustion and loss of availability.

CVSS severity5.9
Medium
EPSS probability1.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in affected Undici WebSocket clients allows remote attackers to crash Node.js processes via compressed server frames. PerMessageDeflate.decompress() retains every decompressed chunk and concatenates them without limiting the expanded data size. Exposure requires permessage-deflate negotiation with an attacker-controlled WebSocket server; the bounded consequence is process memory exhaustion and loss of availability.

The record

CVE
CVE-2026-1526
Published
Mar 12, 2026
Updated
Mar 12, 2026
Vendor
Node.js
Product
Undici
Classifications
CWE-409, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 12, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 12, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 6.24.0; 7.0.0 < 7.24.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Node.js · Undiciversion=< 6.24.0; 7.0.0 < 7.24.0

Published CVSS scores

7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.9Node.js undici maintainersCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-409Improper Handling of Highly Compressed Data (Data Amplification)
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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