CVE-2026-54742Public exploitNetwork attack vectorHinoki check available

Cross-community post featuring via missing ownership check

Published Aug 19, 2026 · Updated Aug 20, 2026

Incorrect authorization in federated Featured handling in LemmyNet Lemmy before 0.19.19 and 1.0.0-alpha.20 allows remote authenticated users to alter post featuring across communities. In crates/apub/activities/src/community/collection_add.rs and collection_remove.rs, the receive handlers dereference self.object as an ApubPost and update featured_community after verify_mod_action without checking that post.community_id matches community.id. Reachability requires moderator rights in any community and federation to a peer instance; the result is unauthorized pinning or unpinning of unrelated posts in featured feeds and listings.

CVSS severity5.1
Medium
EPSS probability0.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Incorrect authorization in federated Featured handling in LemmyNet Lemmy before 0.19.19 and 1.0.0-alpha.20 allows remote authenticated users to alter post featuring across communities. In crates/apub/activities/src/community/collection_add.rs and collection_remove.rs, the receive handlers dereference self.object as an ApubPost and update featured_community after verify_mod_action without checking that post.community_id matches community.id. Reachability requires moderator rights in any community and federation to a peer instance; the result is unauthorized pinning or unpinning of unrelated posts in featured feeds and listings.

The record

CVE
CVE-2026-54742
Published
Aug 19, 2026
Updated
Aug 20, 2026
Vendor
LemmyNet
Product
Lemmy
Classifications
CWE-863
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.20

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.20

Published CVSS scores

5.1GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA: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-863Incorrect Authorization

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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