VulnerabilityPublished 22 Jun 2026Updated 12 Aug 2026

CVE-2026-54353: @budibase/backend-core has potential SSRF DNS rebinding bypass in outbound fetch validation

Affects @budibase/backend-coreSource GCVE Database

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Not known to be exploited · CVSS 8.5 High : upgrade to 3.39.9 soon.

Data as of 11 Nov 2026, 23:24 UTC

CVSS 3.1 base score

8.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3.39.9

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Changed
Confidentiality: High
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 22 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 11 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade @budibase/backend-core to 3.39.9.

Affected software

Product	Affected	Fixed in
npm@budibase/backend-core	Affected <3.39.9	Fixed in 3.39.9

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch is available for this vulnerability. Users should upgrade @budibase/backend-core to version 3.39.9 or later where the issue is fixed. Until patched, avoid granting automation permissions to untrusted users and restrict access to the affected automation features. The vendor advisory confirms the availability of an official fix. No alternative mitigations are specified in the advisory.

Description

Authenticated users with automation permissions in Budibase backend-core versions prior to 3.39.9 can exploit a Server-Side Request Forgery (SSRF) vulnerability via DNS rebinding. The vulnerability arises because the hostname validation and the actual DNS resolution for outbound fetch requests are performed separately, allowing an attacker-controlled hostname to resolve to a public IP during validation and a private/internal IP during the actual connection. This enables non-blind SSRF attacks against internal services including loopback, RFC1918 ranges, and cloud metadata endpoints. The vulnerability affects multiple automation steps that perform outbound fetches, potentially exposing sensitive internal resources and cloud credentials.

Impact

Successful exploitation allows authenticated users with automation permissions to perform SSRF attacks against internal network resources accessible from the Budibase host. This includes access to loopback interfaces (127.0.0.1), private IP ranges (RFC1918), internal Kubernetes or VPC services, and cloud metadata endpoints (169.254.169.254). On cloud deployments without IMDSv2 enforcement, attackers may retrieve temporary IAM credentials from metadata endpoints. In multi-tenant hosted environments, this could lead to cross-tenant access via shared internal infrastructure. The SSRF is non-blind, meaning response data from internal services can be directly observed in automation outputs, increasing the risk and ease of exploitation.

Summary

The vulnerability in @budibase/backend-core (CVE-2026-54353) is a DNS rebinding SSRF bypass affecting the outbound fetch validation flow. The system validates hostnames against a blacklist by resolving DNS once, but the actual socket connection performs a separate DNS lookup via node-fetch, which is not pinned to the validated IPs. An attacker controlling DNS can return a public IP during validation to bypass the blacklist and then a private/internal IP during the real connection, enabling SSRF to internal services such as loopback, private networks, Kubernetes/VPC services, and cloud metadata endpoints. This affects various automation steps including outgoing webhooks and integrations with Slack, Discord, and others. The vulnerability allows non-blind SSRF, as some steps return upstream response content directly in automation outputs. The issue is due to a classic TOCTOU DNS rebinding problem in the validation and fetch implementation.

CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.
Implementation
The most basic advice for TOCTOU vulnerabilities is to not perform a check before the use. This does not resolve the underlying issue of the execution of a function on a resource whose state and identity cannot be assured, but it does help to limit the false sense of security given by the check.
Implementation
When the file being altered is owned by the current user and group, set the effective gid and uid to that of the current user and group when executing this statement.
Architecture and Design
Limit the interleaving of operations on files from multiple processes.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
OWASP ASVS 4.0.3
V1.11.3 (opens in a new tab)
V11.1.6 (opens in a new tab)
V1.11.2 (opens in a new tab)
Attack patterns
Leveraging Race Conditions via Symbolic Links (opens in a new tab)
Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-918Server-Side Request Forgery (opens in a new tab)
Base weaknessCWE Top 25 (2025): #22OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.
Implementation · Operation
If there is a known list of applications, IP, hostname, and/or domains to which the product is allowed to communicate, then use allowlists to ensure that outgoing requests are restricted to these known entities. The allowlists could be in the application code or possibly enforced by firewalls or network segmentation.
Implementation · Operation
If the product is expected to be able to connect to arbitrary IP addresses or domains, consider using a denylist that includes private network addresses, internal domain names, etc. The denylist could be in the application code or possibly enforced by firewalls or network segmentation.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
OWASP Cheat Sheets
Server Side Request Forgery Prevention (opens in a new tab)
Unvalidated Redirects and Forwards (opens in a new tab)
Cross Site Scripting Prevention (opens in a new tab)
DOM based XSS Prevention (opens in a new tab)
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V12.6.1 (opens in a new tab)
V5.2.6 (opens in a new tab)
Attack patterns
Server Side Request Forgery (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 12 Aug 2026, 20:57 UTC

WeaknessesCWE-367, CWE-918

Technical details

References

Community reviews

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