CVE-2023-49095Network attack vector

Unauthenticated impersonation via unverified ActivityPub inbox requests

Published Nov 30, 2023 · Updated Nov 27, 2024

Improper request validation in Concorde before 12.122.2 allows remote attackers to impersonate remote users through its ActivityPub inbox. The inbox handler in packages/backend/src/server/activitypub.ts passed a parsed HTTP signature and request body to queue processing without validating the body digest or matching the signed Host header to the configured host. Exposure requires a deployment that forwards mismatched Host headers or exposes the application port directly; successful requests can attribute forged federated activity to another user.

CVSS severity8.6
High
EPSS probability0.56%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper request validation in Concorde before 12.122.2 allows remote attackers to impersonate remote users through its ActivityPub inbox. The inbox handler in packages/backend/src/server/activitypub.ts passed a parsed HTTP signature and request body to queue processing without validating the body digest or matching the signed Host header to the configured host. Exposure requires a deployment that forwards mismatched Host headers or exposes the application port directly; successful requests can attribute forged federated activity to another user.

The record

CVE
CVE-2023-49095
Published
Nov 30, 2023
Updated
Nov 27, 2024
Vendor
nexryai
Product
Concorde
Classifications
CWE-20, T1656
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 30, 2023CVE publishedPublication date reported by the CVE source.
  2. Nov 27, 2024Record 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=< 12.122.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

nexryai · Concordeversion=< 12.122.2

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
8.6GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/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.

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-20Improper Input Validation
T1656Impersonation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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