Cyber Resilience

CVE-2025-25306

Misskey ≤ 2025.2.1

Published
10 March 2025
Modified
26 November 2025
Patch / advisory
View advisory
CVSS Score v3.1 9.3
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N
EPSS Score 0.0017 7th percentile
Risk Priority 64 floored blend · peak EPSS

Summary

CVE-2025-25306 is a critical-severity Origin Validation Error (CWE-346) vulnerability in Misskey Misskey. Its CVSS base score is 9.3 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique DHCP Spoofing (T1557.003); ranked at the 7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to AC-16 (Security and Privacy Attributes) and AC-4 (Information Flow Enforcement) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2025-25306 is a vulnerability in Misskey, an open source, federated social media platform based on ActivityPub. The issue stems from an incomplete patch for the prior CVE-2024-52591, which failed to properly validate the relationship between the `id` and `url` fields in ActivityPub objects. This allows attackers to forge objects that claim authority via the `url` field, even for object types that require authority in the `id` field. Affected versions are those prior to 2025.2.1, with a CVSS v3.1 base score of 9.3 (AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N) and associated CWEs including CWE-346 (Origin Validation Error), CWE-441 (Unintended Proxy or Intermediary), and CWE-1025 (Comparison Using Non-Equal Operators).

Unauthenticated attackers can exploit this remotely with low complexity and no user interaction, leveraging the federated nature of Misskey to send malicious ActivityPub objects from remote instances. Successful exploitation enables high integrity impacts, such as forging authoritative objects to impersonate entities or manipulate federated content, alongside low confidentiality effects, while scope changes amplify the consequences across instances.

Misskey version 2025.2.1 fully addresses the vulnerability through improved validation of `id` and `url` relations in ActivityPub objects. Security practitioners should update to this release immediately, as detailed in the official advisory (GHSA-6w2c-vf6f-xf26) and release notes (2025.2.1 tag).

OWASP Top 10 for Web (2025)

A01:2025 Broken Access ControlA07:2025 Authentication Failures

EU & UK References

Vulnerability Data

Misskey is an open source, federated social media platform. The patch for CVE-2024-52591 did not sufficiently validate the relation between the `id` and `url` fields of ActivityPub objects. An attacker can forge an object where they claim authority in the…

more

`url` field even if the specific ActivityPub object type require authority in the `id` field. Version 2025.2.1 addresses the issue.

CWE(s)
CWE-346CWE-441CWE-1025

Related Threats

MITRE ATT&CK Enterprise Techniques

T1557.003 DHCP Spoofing Credential Access
Adversaries may redirect network traffic to adversary-owned systems by spoofing Dynamic Host Configuration Protocol (DHCP) traffic and acting as a malicious DHCP server on the victim network.
attack.mitre.org →
T1090 Proxy Command And Control
Adversaries may use a connection proxy to direct network traffic between systems or act as an intermediary for network communications to a command and control server to avoid direct connections to their infrastructure.
attack.mitre.org →
T1090.002 External Proxy Command And Control
Adversaries may use an external proxy to act as an intermediary for network communications to a command and control server to avoid direct connections to their infrastructure.
attack.mitre.org →
T1557 Adversary-in-the-Middle Credential Access
Adversaries may attempt to position themselves between two or more networked devices using an adversary-in-the-middle (AiTM) technique to support follow-on behaviors such as [Network Sniffing](https://attack.
attack.mitre.org →
T1557.001 Name Resolution Poisoning and SMB Relay Credential Access
By responding to LLMNR/NBT-NS/mDNS network traffic, adversaries may spoof an authoritative source for name resolution to force communication with an adversary controlled system.
attack.mitre.org →
T1557.002 ARP Cache Poisoning Credential Access
Adversaries may poison Address Resolution Protocol (ARP) caches to position themselves between the communication of two or more networked devices.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-24897Same product: Misskey Misskey
CVE-2023-43793Same product: Misskey Misskey
CVE-2023-24812Same product: Misskey Misskey
CVE-2025-46559Same product: Misskey Misskey
CVE-2025-24896Same product: Misskey Misskey
CVE-2026-28433Same product: Misskey Misskey
CVE-2024-25636Same product: Misskey Misskey
CVE-2024-52579Same product: Misskey Misskey
CVE-2024-52591Same product: Misskey Misskey
CVE-2023-25154Same product: Misskey Misskey

Affected Assets

misskey
misskey
≤ 2025.2.1

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 3 hardening rules · 1 OS baseline
Validate
Prove the fix (OWASP ASVS)
  • V3.2.1
  • V3.5.1
  • V3.5.3
  • V3.5.8

Mitigating Controls (NIST 800-53 r5) AI

AC-16 Security and Privacy Attributes good match

Associating and preserving security attributes such as original source identity prevents the loss of provenance that creates the confused deputy.

AC-4 Information Flow Enforcement good match

Information flow enforcement directly requires validating the source of data before allowing transmission or receipt.

IA-3 Device Identification and Authentication good match

Device identification and authentication mandates verifying the source before establishing connections.

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation can discover incorrect comparison logic after implementation but does not stop the flaw from being written.

SC-23 Session Authenticity good match

Session authenticity mechanisms require validation that communications originate from the expected party.

AC-3 Access Enforcement partial match

Access enforcement directly stops a component from acting on forwarded requests without verifying original source authorizations.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.AA-03 mostly match
prevents

Authentication directly verifies the source of users/services/hardware, mitigating origin validation failures.

PR.AA-04 mostly match
prevents

Verifying identity assertions enforces origin validation for conveyed claims.

PR.PS-06 mostly match
prevents

Secure SDLC activities such as code review and logic testing directly prevent incorrect comparison factors in code.

ID.AM-03 partial match
prevents

Documenting authorized flows supports origin validation by defining expected sources.

PR.AA-05 partial match
prevents

Enforcing least-privilege authorizations on forwarded requests reduces confused-deputy abuse even if source identity is lost.

PR.IR-01 partial match
prevents

Protecting networks from unauthorized access requires origin checks on communication sources.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect incorrect comparison results during development and acceptance.

A.5.15 Access control partial match
prevents

Access-control rules can limit which upstream identities may cause the product to act on their behalf, reducing confused-deputy risk.

A.5.16 Identity management partial match
prevents

Proper identity management ensures the original requester identity is preserved and validated before the product forwards requests.

A.5.18 Access rights partial match
degrades

Explicit access-rights assignment can restrict the product’s ability to act as an unintended proxy for external actors.

A.8.2 Privileged access rights partial match
degrades

Privileged-access controls limit the rights the product may exercise on behalf of upstream callers, mitigating confused-deputy abuse.

A.8.20 Networks security partial match
mitigates

Network security controls enforce origin validation at network boundaries.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).

Oracle Linux 8 (3 rules)
  • V-248574 YUM must be configured to prevent the installation of patches, service packs, device drivers, or OL 8 system components that have not been digitally signed using a certificate that is recognized and approved by the organization. prevents CWE-346
  • V-248575 OL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-346
  • V-248827 OL 8 must not have the rsh-server package installed. prevents CWE-346

References