CVE-2026-54739

MEDIUMPre-NVD 6.96.9
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This medium-severity CVE scores 6.9 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.6% (48th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source

Also known asEUVD-2026-62847 (ENISA EUVD)Source: ENISA EUVD

6.9EG
EchelonGraph verdictMonitorRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 6.9Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Lemmy is a link aggregator and forum for the fediverse. Prior to 0.19.19 and 1.0.0-beta.1, Lemmy's login endpoint in crates/api/api/src/local_user/login.rs returns different errors depending on whether the username_or_email value exists. LocalUserView::find_by_email_or_name propagates a NotFound response for an unknown account, while an existing account with a wrong password returns LemmyErrorType::IncorrectLogin. This observable response discrepancy, including HTTP 404 for a nonexistent account and HTTP 400 for an incorrect password on an existing account, allows an unauthenticated attacker to confirm registered usernames or email addresses and use the results for targeted credential attacks or social engineering. This issue is fixed in versions 0.19.19 and 1.0.0-beta.1.

CVSS v3
6.9
EG Score
6.9MEDIUMmedium confidence
EG Risk
46
EG Risk 46/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity69% × 45%
Impact severity (EG Severity): CVSS 6.9 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.6% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.6%
EPSS %ILE
48th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (6.9): severity, escalated by confirmed exploitation. This CVE's 6.9 is its impact severity (EG Severity), not escalated.

EG Severity
6.9 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
EG Likelihood
0.6% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-24). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

August 19, 2026

Last Modified

September 9, 2026

Advisory Details (8)

Auto-updated Aug 19, 2026
Patch available. Sources: github, github_pr, github_commit, github_release.
Web page

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-beta.1

Patch available: LemmyNet/lemmy 1.0.0-beta.1 (pre-release)

https://github.com/LemmyNet/lemmy/releases/tag/1.0.0-beta.1
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 59e968a5ac36 (LemmyNet/lemmy)

Patch available: LemmyNet/lemmy 0.19.19 (contains commit 59e968a5ac36)

https://github.com/LemmyNet/lemmy/commit/59e968a5ac36d36d08a59028e2dbb92641536964
GitHub commit Patch Available

commit 4d235a1b668b (LemmyNet/lemmy)

Patch available: LemmyNet/lemmy 1.0.0-beta.1 (contains commit 4d235a1b668b)

https://github.com/LemmyNet/lemmy/commit/4d235a1b668b7dda6b73dbbc9ca289bb40acfa83
GitHub pull request Patch Available

[0.19] Prevent user enumeration via login endpoint

Patch available: LemmyNet/lemmy 0.19.19 (PR #6535 merged 2026-05-27)

https://github.com/LemmyNet/lemmy/pull/6535
GitHub pull request Patch Available

Prevent user enumeration via login endpoint

Patch available: LemmyNet/lemmy 1.0.0-beta.1 (PR #6531 merged 2026-06-01)

https://github.com/LemmyNet/lemmy/pull/6531
GitHub advisoryMentions a patch (unverified)

Login Endpoint User Enumeration via HTTP Response Code Differential · Advisory · LemmyNet/lemmy · GitHub

https://github.com/LemmyNet/lemmy/security/advisories/GHSA-xgg7-8hvq-8m65

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 42× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 121 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 21 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-02 16:45 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  2. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  3. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  4. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  5. 2026-10-30 11:25 UTCOSV refresh
  6. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  7. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  8. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  9. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  10. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  11. 2026-10-25 14:19 UTCEG score recompute
  12. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  13. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  14. 2026-10-22 21:19 UTCEG score recompute
  15. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  16. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  17. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  18. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  19. 2026-10-18 03:30 UTCEG score recompute
  20. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  21. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  22. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  23. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  24. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  25. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.6% · 46th percentile
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  1. 2026-10-12 15:56 UTCEG score recompute
  2. 2026-10-11 19:39 UTCEG score recompute
  3. 2026-10-11 16:54 UTCEG score recompute
  4. 2026-10-11 14:17 UTCEG score recompute
  5. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  6. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  7. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  8. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  9. 2026-10-08 06:36 UTCEG score recompute
  10. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  11. 2026-10-07 02:13 UTCEG score recompute
  12. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.6% · 46th percentile
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  14. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.6% · 46th percentile
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  18. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.6% · 46th percentile
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  20. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.6% · 46th percentile
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  22. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.6% · 46th percentile
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  24. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.6% · 46th percentile
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  26. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  27. 2026-09-29 02:41 UTCEG score recompute
  28. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.6% · 46th percentile
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  30. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  31. 2026-09-27 05:57 UTCEG score recompute
  32. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.6% · 46th percentile
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  34. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  35. 2026-09-23 22:17 UTCEG score recompute
  36. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  37. 2026-09-22 23:56 UTCEG score recompute
  38. 2026-09-22 01:33 UTCEG score recompute
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  40. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  41. 2026-09-20 04:41 UTCEG score recompute
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  43. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  44. 2026-09-18 07:54 UTCEG score recompute
  45. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  46. 2026-09-17 09:31 UTCEG score recompute
  47. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  48. 2026-09-16 11:09 UTCEG score recompute
  49. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.4% · 36th percentile
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  53. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  54. 2026-09-12 17:41 UTCEG score recompute
  55. 2026-09-11 19:19 UTCEG score recompute
  56. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  57. 2026-09-10 20:57 UTCEG score recompute
  58. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.4% · 36th percentile
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  75. 2026-08-30 07:44 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-54739?
CVE-2026-54739 is a medium-severity vulnerability; its CVE record was published on August 19, 2026. Lemmy is a link aggregator and forum for the fediverse. Prior to 0.19.19 and 1.0.0-beta.1, Lemmy's login endpoint in crates/api/api/src/local_user/login.rs returns different errors depending on whether the username_or_email value exists. LocalUserView::find_by_email_or_name propagates a NotFound…
When was the CVE record for CVE-2026-54739 published?
The CVE record for CVE-2026-54739 was published on August 19, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 9, 2026; the record at its source may have been updated since.
Is CVE-2026-54739 actively exploited?
CVE-2026-54739 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (48th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-54739?
CVE-2026-54739 has a CVSS base score of 6.9 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-54739?
A fix for CVE-2026-54739 is available: update to the fixed version the vendor names in its advisory.

Dependency Blast Radius

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