CVE-2026-39820Network attack vector

Service interruption via quadratic comment concatenation

Published May 7, 2026 · Updated Aug 28, 2026

Resource exhaustion in Go net/mail before 1.25.10 and 1.26.0 through 1.26.2 allows remote attackers to interrupt services via crafted email input. The consumeComment parser repeatedly concatenates attacker-controlled comment fragments while ParseAddress, ParseAddressList, or ParseDate processes them, causing quadratic CPU work and excessive memory allocation. Exposure requires an application to pass untrusted email data to one of those parsers; successful exploitation can hang or crash the processing service without reading or altering data.

CVSS severity7.5
High
EPSS probability0.78%
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 Go net/mail before 1.25.10 and 1.26.0 through 1.26.2 allows remote attackers to interrupt services via crafted email input. The consumeComment parser repeatedly concatenates attacker-controlled comment fragments while ParseAddress, ParseAddressList, or ParseDate processes them, causing quadratic CPU work and excessive memory allocation. Exposure requires an application to pass untrusted email data to one of those parsers; successful exploitation can hang or crash the processing service without reading or altering data.

The record

CVE
CVE-2026-39820
Published
May 7, 2026
Updated
Aug 28, 2026
Vendor
389 Directory Server
Product
Assisted Installer for OpenShift Container Platform
Classifications
CWE-606, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 28, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

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 · Assisted Installer for OpenShift Container PlatformAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Service Mesh 2Affected versions are unavailable in this record.
389 Directory Server · Red Hat QuayAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift ServerlessAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift LightspeedAffected versions are unavailable in this record.
389 Directory Server · Red Hat Service InterconnectAffected versions are unavailable in this record.
389 Directory Server · cert-manager Operator for Red Hat OpenShiftAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift AIAffected versions are unavailable in this record.
389 Directory Server · OpenShift API for Data ProtectionAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Dev SpacesAffected versions are unavailable in this record.
389 Directory Server · OpenShift Developer Tools and ServicesAffected versions are unavailable in this record.
389 Directory Server · Red Hat Ceph StorageAffected versions are unavailable in this record.
389 Directory Server · Red Hat Developer HubAffected versions are unavailable in this record.
389 Directory Server · Migration Toolkit for ApplicationsAffected versions are unavailable in this record.
389 Directory Server · Security Profiles OperatorAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux AIAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Data FoundationAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Container Platform 4.21Affected versions are unavailable in this record.
389 Directory Server · Zero Trust Workload Identity Manager - Tech PreviewAffected versions are unavailable in this record.
Go standard library · net/mailversion=0 <1.25.10; version=1.26.0-0 <1.26.3
389 Directory Server · Red Hat Advanced Cluster Security for KubernetesAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Container Platform 4.18Affected versions are unavailable in this record.
389 Directory Server · Red Hat Migration Toolkit for ContainersAffected versions are unavailable in this record.
389 Directory Server · External Secrets Operator for Red Hat OpenShiftAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 9.4 Update Services for SAP SolutionsAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 10Affected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift VirtualizationAffected versions are unavailable in this record.
389 Directory Server · File Integrity OperatorAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Container Platform 4.19Affected versions are unavailable in this record.
389 Directory Server · Red Hat Hardened ImagesAffected versions are unavailable in this record.
389 Directory Server · Red Hat Ceph Storage 9Affected versions are unavailable in this record.
389 Directory Server · Multiarch Tuning OperatorAffected versions are unavailable in this record.
389 Directory Server · Logical Volume Manager StorageAffected versions are unavailable in this record.
389 Directory Server · Workload Availability for Red Hat OpenShiftAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift GitOpsAffected versions are unavailable in this record.
389 Directory Server · Confidential Compute Attestation OperatorAffected versions are unavailable in this record.
389 Directory Server · Power monitoring for Red Hat OpenShiftAffected versions are unavailable in this record.
389 Directory Server · Red Hat Certification Program for Red Hat Enterprise Linux 9Affected versions are unavailable in this record.
389 Directory Server · Zero Trust Workload Identity ManagerAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift distributed tracing platformAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift LoggingAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Container PlatformAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Cluster Manager CLIAffected versions are unavailable in this record.
389 Directory Server · Red Hat build of CryostatAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 9Affected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift PipelinesAffected versions are unavailable in this record.
389 Directory Server · multicluster engine for KubernetesAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Container Platform 4Affected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Dev Workspaces OperatorAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 10.0 Extended Update SupportAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Service Mesh 3Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 9.6 Extended Update SupportAffected versions are unavailable in this record.
389 Directory Server · Red Hat Trusted Artifact SignerAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8Affected versions are unavailable in this record.
389 Directory Server · Logging Subsystem for Red Hat OpenShiftAffected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Container Platform 4.20Affected 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-606Unchecked Input for Loop Condition
T1499Endpoint Denial of Service

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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