CVE-2026-90448Network attack vector

Authenticated record overwrite via unrestricted API methods

Published Sep 11, 2026 · Updated Sep 11, 2026

Improper access control in Malcolm before 26.06.0 allows remote authenticated users to overwrite OpenSearch records through the read-only interface. The /mapi location in nginx_readonly.conf authenticates requests but fails to limit methods, so POST /mapi/event indexes attacker-controlled documents with the API service account. Exploitation requires a valid account and the temporary read-only mode; a known document identifier permits replacement of an existing record.

CVSS severityUnavailable
Unscored
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in Malcolm before 26.06.0 allows remote authenticated users to overwrite OpenSearch records through the read-only interface. The /mapi location in nginx_readonly.conf authenticates requests but fails to limit methods, so POST /mapi/event indexes attacker-controlled documents with the API service account. Exploitation requires a valid account and the temporary read-only mode; a known document identifier permits replacement of an existing record.

The record

CVE
CVE-2026-90448
Published
Sep 11, 2026
Updated
Sep 11, 2026
Vendor
Cybersecurity and Infrastructure Security Agency (CISA)
Product
Malcolm
Classifications
T1565.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

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

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

  1. Affected versionversion=0 <v26.06.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Cybersecurity and Infrastructure Security Agency (CISA) · Malcolmversion=0 <v26.06.0

Published CVSS scores

No CVSS assessment is available in this record.

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.

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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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1565.001Stored Data Manipulation

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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