CVE-2026-15561Network attack vector

Service outage via unbounded chunked trailer accumulation

Published Aug 11, 2026 · Updated Aug 11, 2026

Denial of service in Red Hat JBoss EAP Undertow allows remote attackers to stop listener deployments via crafted chunked trailers. The ChunkReader TrailerParser accepts unlimited trailer bytes and fields after the terminal zero chunk, accumulates them in a HeaderMap, and excludes them from max-entity-size accounting. A single unauthenticated TCP connection can exhaust JVM memory on direct-edge or L4-proxied listeners; an L7 re-framing proxy blocks the payload.

CVSS severity7.5
High
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Red Hat JBoss EAP Undertow allows remote attackers to stop listener deployments via crafted chunked trailers. The ChunkReader TrailerParser accepts unlimited trailer bytes and fields after the terminal zero chunk, accumulates them in a HeaderMap, and excludes them from max-entity-size accounting. A single unauthenticated TCP connection can exhaust JVM memory on direct-edge or L4-proxied listeners; an L7 re-framing proxy blocks the payload.

The record

CVE
CVE-2026-15561
Published
Aug 11, 2026
Updated
Aug 11, 2026
Vendor
389 Directory Server
Product
Red Hat JBoss Enterprise Application Platform 8
Classifications
CWE-770, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 11, 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?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

389 Directory Server · Red Hat JBoss Enterprise Application Platform 8Affected versions are unavailable in this record.
389 Directory Server · Red Hat JBoss Enterprise Application Platform 7Affected versions are unavailable in this record.
389 Directory Server · Red Hat JBoss Enterprise Application PlatformAffected versions are unavailable in this record.

Published CVSS scores

7.5Red HatCVSS:3.1/AV:N/AC:L/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-770Allocation of Resources Without Limits or Throttling
T1499.003Application Exhaustion Flood

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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