CVE-2026-72859Public exploitNetwork attack vector

Unauthorized S3 writes via downgraded route permission

Published Aug 14, 2026 · Updated Aug 14, 2026

Incorrect authorization in Budibase Server 3.39.4 before 3.40.0 allows remote authenticated users to mint arbitrary S3 PUT URLs. The attachment URL route accepts TABLE/WRITE permission instead of BUILDER permission, while its controller passes a caller-supplied bucket to the S3 signer. BASIC access and a valid S3 datasource ID are required; successful use permits file writes to buckets reachable by the stored IAM credentials.

CVSS severity7.7
High
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect authorization in Budibase Server 3.39.4 before 3.40.0 allows remote authenticated users to mint arbitrary S3 PUT URLs. The attachment URL route accepts TABLE/WRITE permission instead of BUILDER permission, while its controller passes a caller-supplied bucket to the S3 signer. BASIC access and a valid S3 datasource ID are required; successful use permits file writes to buckets reachable by the stored IAM credentials.

The record

CVE
CVE-2026-72859
Published
Aug 14, 2026
Updated
Aug 14, 2026
Vendor
Budibase
Product
Budibase Server
Classifications
CWE-863, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 14, 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=3.39.4 <3.40.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Budibase · Budibase Serverversion=3.39.4 <3.40.0

Published CVSS scores

8.3VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N
7.7BudibaseCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N

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 exploitPublished

Weakness, pattern, technique

CWE-863Incorrect Authorization
T1190Exploit Public-Facing Application

Public exploit references

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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