CVE-2026-54742

MEDIUMPre-NVD 5.15.1—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.1 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 65% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
5.1EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.1Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Lemmy is a link aggregator and forum for the fediverse. From 0.19.18 until 0.19.19 and 1.0.0-alpha.20, a community moderator can feature or unfeature posts in other communities through federated CollectionAdd and CollectionRemove activities using CollectionType::Featured. After verify_mod_action authorizes the actor against self.community(), the receive handlers in crates/apub/activities/src/community/collection_add.rs and crates/apub/activities/src/community/collection_remove.rs dereference self.object as an ApubPost and update featured_community without verifying that post.community_id equals community.id. A moderator can therefore target an unrelated post owned by another community, push it into featured feeds and listings, or undo another community's legitimate curation decision. This issue is fixed in versions 0.19.19 and 1.0.0-alpha.20.

CVSS v3
5.1
EG Score
5.1(medium)
EG Risk
39(Track)
EG Risk 39/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity51% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
35%
KEV
Not listed

Published

August 19, 2026

Last Modified

August 20, 2026

Advisory Details (8)

Auto-updated Aug 19, 2026
🔬 Proof of concept available. Patch available. Sources: github_pr, github_commit, github_release, github.
generic

2026-06-09 - Lemmy Release v0.19.19

https://join-lemmy.org/news/2026-06-09_-_Lemmy_Release_v0.19.19
github_release Patch Available

1.0.0-alpha.20

Patch available: LemmyNet/lemmy 1.0.0-alpha.20 (pre-release)

https://github.com/LemmyNet/lemmy/releases/tag/1.0.0-alpha.20
github_release Patch Available

0.19.19

Patch available: LemmyNet/lemmy 0.19.19

https://github.com/LemmyNet/lemmy/releases/tag/0.19.19
github_commit Patch Available

commit abe256243822 (LemmyNet/lemmy)

Patch available: LemmyNet/lemmy 0.19.19 (contains commit abe256243822)

https://github.com/LemmyNet/lemmy/commit/abe256243822526dcd4bca857f7c0adeb49944f5
github_commit Patch Available

commit 108d78c592cc (LemmyNet/lemmy)

Patch available: LemmyNet/lemmy 1.0.0-beta.0 (contains commit 108d78c592cc)

https://github.com/LemmyNet/lemmy/commit/108d78c592cc88bac2b0bf52ca6631be54f6fb23
github_pr Patch Available

For federated post feature, write modlog and validate community

Patch available: LemmyNet/lemmy 1.0.0-beta.0 (PR #6501 merged 2026-05-18)

https://github.com/LemmyNet/lemmy/pull/6501
github_pr Patch Available

[0.19] For federated post feature, write modlog and validate community

Patch available: LemmyNet/lemmy 0.19.19 (PR #6500 merged 2026-05-18)

https://github.com/LemmyNet/lemmy/pull/6500
github Patch Available🟡 PoC Available

`CollectionAdd::Featured` does not check the post is in the community · Advisory · LemmyNet/lemmy · GitHub

https://github.com/LemmyNet/lemmy/security/advisories/GHSA-gwfj-h8r7-792v

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 11× in last 7d / 21× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-30 01:22 UTCEPSS rescore
  2. 2026-08-29 14:18 UTCEG score recompute
  3. 2026-08-28 21:41 UTCEPSS rescore
  4. 2026-08-27 15:37 UTCEG score recompute
  5. 2026-08-27 14:25 UTCEPSS rescore
  6. 2026-08-26 16:14 UTCEG score recompute
  7. 2026-08-26 14:46 UTCEPSS rescore
  8. 2026-08-25 16:37 UTCEG score recompute
  9. 2026-08-25 13:49 UTCEPSS rescore
  10. 2026-08-24 17:23 UTCEG score recompute
  11. 2026-08-23 18:05 UTCEG score recompute
  12. 2026-08-23 00:19 UTCEPSS rescore
  13. 2026-08-22 18:50 UTCEG score recompute
  14. 2026-08-21 23:49 UTCEPSS rescore
  15. 2026-08-21 19:35 UTCEG score recompute
  16. 2026-08-20 22:55 UTCEPSS rescore
  17. 2026-08-20 20:20 UTCEG score recompute
  18. 2026-08-20 20:17 UTCEG score recompute
  19. 2026-08-19 20:19 UTCEG score recompute
  20. 2026-08-19 20:13 UTCEG score recompute
  21. 2026-08-19 20:12 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-54742?
CVE-2026-54742 is a medium vulnerability published on August 19, 2026. Lemmy is a link aggregator and forum for the fediverse. From 0.19.18 until 0.19.19 and 1.0.0-alpha.20, a community moderator can feature or unfeature posts in other communities through federated CollectionAdd and CollectionRemove activities using CollectionType::Featured. After verifymodaction…
When was CVE-2026-54742 disclosed?
CVE-2026-54742 was first published in the National Vulnerability Database on August 19, 2026, with the most recent update on August 20, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-54742 actively exploited?
CVE-2026-54742 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 65.2% of all scored CVEs.
What is the CVSS score of CVE-2026-54742?
CVE-2026-54742 has a CVSS v3 base score of 5.1 (NVD).
How do I remediate CVE-2026-54742?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-54742, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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