CVE-2026-81421Public exploitNetwork attack vector

Internal service access via unvalidated endpoint URLs

Published Aug 26, 2026 · Updated Aug 27, 2026

Server-side request forgery in ddfourtwo sentry-selfhosted-mcp 0.4.0 allows remote attackers to access internal services via endpoint URLs. The raw_sentry_api handler passes its caller-controlled endpoint directly to Axios GET, POST, PUT, or DELETE without rejecting absolute, loopback, link-local, or private addresses. Exploitation requires access to invoke the MCP tool and outbound connectivity from its process, enabling requests to otherwise unreachable internal services.

CVSS severity7.3
High
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Server-side request forgery in ddfourtwo sentry-selfhosted-mcp 0.4.0 allows remote attackers to access internal services via endpoint URLs. The raw_sentry_api handler passes its caller-controlled endpoint directly to Axios GET, POST, PUT, or DELETE without rejecting absolute, loopback, link-local, or private addresses. Exploitation requires access to invoke the MCP tool and outbound connectivity from its process, enabling requests to otherwise unreachable internal services.

The record

CVE
CVE-2026-81421
Published
Aug 26, 2026
Updated
Aug 27, 2026
Vendor
ddfourtwo
Product
sentry-selfhosted-mcp
Classifications
CWE-918, CAPEC-664, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 26, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 27, 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=0.4.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ddfourtwo · sentry-selfhosted-mcpversion=0.4.0

Published CVSS scores

7.3INCIBE-CERTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
7.5INCIBE-CERTAV:N/AC:L/Au:N/C:P/I:P/A:P
5.5INCIBE-CERTCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P

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 exploitPublished

Weakness, pattern, technique

CWE-918Server-Side Request Forgery (SSRF)
CAPEC-664Server Side Request Forgery
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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