CVE-2026-54740Public exploitNetwork attack vectorHinoki check available

Moderator removal via skipped rank check

Published Aug 19, 2026 · Updated Aug 20, 2026

Missing authorization in Lemmy before 0.19.19 and 1.0.0-alpha.18 allows remote authenticated users to remove higher-ranked moderators. In crates/apub/activities/src/community/collection_remove.rs, CollectionRemove::verify only confirms moderator status, and CollectionRemove::receive dereferences the target moderator and calls CommunityActions::leave without applying LocalUser::is_higher_mod_or_admin_check to the person named in the object field. Exploitation requires a valid lower-ranked federated moderator in a community with remote moderators; the result is unauthorized removal of senior moderators from that community's moderator list.

CVSS severity6.5
Medium
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Missing authorization in Lemmy before 0.19.19 and 1.0.0-alpha.18 allows remote authenticated users to remove higher-ranked moderators. In crates/apub/activities/src/community/collection_remove.rs, CollectionRemove::verify only confirms moderator status, and CollectionRemove::receive dereferences the target moderator and calls CommunityActions::leave without applying LocalUser::is_higher_mod_or_admin_check to the person named in the object field. Exploitation requires a valid lower-ranked federated moderator in a community with remote moderators; the result is unauthorized removal of senior moderators from that community's moderator list.

The record

CVE
CVE-2026-54740
Published
Aug 19, 2026
Updated
Aug 20, 2026
Vendor
LemmyNet
Product
Lemmy
Classifications
CWE-862, T1098
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 20, 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=< 0.19.19
  2. Affected versionversion=>= 1.0.0-alpha.0, < 1.0.0-alpha.18

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

LemmyNet · Lemmyversion=< 0.19.19; version=>= 1.0.0-alpha.0, < 1.0.0-alpha.18

Published CVSS scores

6.5GitHubCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-862Missing Authorization
T1098Account Manipulation

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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