CVE-2026-55420

HIGHNVD 8.18.1
EchelonGraph scoreMEDIUM confidence

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

This high-severity CVE scores 8.1 under NVD CVSS v3. EPSS exploit probability: 0.6% (47th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, NVD CVSS v3
8.1EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 8.1Exploit: None knownExposed services: Not assessed

The CVE record names the fixed release — apply it.

Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, under certain non-default configurations, processing of PDF uploads could be exploited to obtain RCE on the server. This issue is patched in 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5.

CVSS v3
8.1
EG Score
8.1HIGHmedium confidence
EG Risk
37
EG Risk 37/100

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 (value × EchelonGraph’s weight)
Severity81% × 45%
The EG Score, 8.1 of 10.
Exploitation0.6% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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: The CVE record names the fixed release. Apply it within your standard update timelines.
EPSS PROB
0.6%
EPSS %ILE
47th
KEV
Not listed

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

The CVE record names the fixed release. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (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

July 9, 2026

Last Modified

July 14, 2026

Advisory Details (2)

Auto-updated Jul 9, 2026
Fix named in the CVE record. Sources: github_commit, github.
GitHub advisoryMentions a patch (unverified)

Remote code execution via pdf uploads · Advisory · discourse/discourse · GitHub

https://github.com/discourse/discourse/security/advisories/GHSA-7wq5-jgww-5rw3
GitHub commit

commit ca5a7e061675 (discourse/discourse)

Fix landed in discourse/discourse commit ca5a7e061675 — awaiting tagged release

https://github.com/discourse/discourse/commit/ca5a7e06167561928556afa2f237d67e459c6914

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 34× 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 141 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 41 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  2. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  3. 2026-10-12 15:55 UTCEG score recompute
  4. 2026-10-11 19:39 UTCEG score recompute
  5. 2026-10-11 16:54 UTCEG score recompute
  6. 2026-10-11 14:17 UTCEG score recompute
  7. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  9. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  10. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  11. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  12. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  13. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  14. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  15. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  16. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  17. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  18. 2026-10-01 16:01 UTCEG score recompute
  19. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  20. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  21. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  22. 2026-09-28 10:27 UTCEG score recompute
  23. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  24. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  25. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.6% · 46th percentile
Show 75 more
  1. 2026-09-24 11:24 UTCEG score recompute
  2. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  3. 2026-09-23 05:54 UTCEG score recompute
  4. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  5. 2026-09-18 05:35 UTCEG score recompute
  6. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  7. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  8. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  9. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  10. 2026-09-13 23:45 UTCEG score recompute
  11. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  12. 2026-09-13 08:18 UTCEG score recompute
  13. 2026-09-12 03:23 UTCEG score recompute
  14. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  15. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  16. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  17. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  18. 2026-09-06 13:59 UTCEG score recompute
  19. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  20. 2026-09-05 22:34 UTCEG score recompute
  21. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  22. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  23. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  24. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  25. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  26. 2026-08-30 06:44 UTCEG score recompute
  27. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  28. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  29. 2026-08-27 21:44 UTCEG score recompute
  30. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  31. 2026-08-27 00:59 UTCEG score recompute
  32. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  33. 2026-08-26 03:49 UTCEG score recompute
  34. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  35. 2026-08-24 22:25 UTCEG score recompute
  36. 2026-08-24 10:58 UTCEG score recompute
  37. 2026-08-23 00:36 UTCEG score recompute
  38. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.3% · 28th percentile
  39. 2026-08-22 01:36 UTCEG score recompute
  40. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.3% · 28th percentile
  41. 2026-08-21 02:42 UTCEG score recompute
  42. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.3% · 28th percentile
  43. 2026-08-20 01:46 UTCEG score recompute
  44. 2026-08-19 17:04 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  45. 2026-08-18 22:27 UTCEG score recompute
  46. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  47. 2026-08-17 22:16 UTCEG score recompute
  48. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  49. 2026-08-16 18:06 UTCEG score recompute
  50. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  51. 2026-08-16 06:38 UTCEG score recompute
  52. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  53. 2026-08-15 07:45 UTCEG score recompute
  54. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  55. 2026-08-14 08:11 UTCEG score recompute
  56. 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  57. 2026-08-12 21:51 UTCEG score recompute
  58. 2026-08-12 13:51 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  59. 2026-08-11 22:56 UTCEG score recompute
  60. 2026-08-11 00:02 UTCEG score recompute
  61. 2026-08-11 00:00 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  62. 2026-08-10 01:08 UTCEG score recompute
  63. 2026-08-09 13:46 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  64. 2026-08-09 02:15 UTCEG score recompute
  65. 2026-08-08 16:37 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  66. 2026-08-08 03:20 UTCEG score recompute
  67. 2026-08-06 16:59 UTCEG score recompute
  68. 2026-08-06 13:47 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  69. 2026-08-06 05:32 UTCEG score recompute
  70. 2026-08-05 19:17 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  71. 2026-08-04 17:13 UTCEG score recompute
  72. 2026-08-04 15:10 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  73. 2026-08-04 10:39 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  74. 2026-08-03 18:19 UTCEG score recompute
  75. 2026-08-03 10:36 UTCEPSS rescoreEPSS 0.3% · 27th percentile

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-55420?
CVE-2026-55420 is a high-severity vulnerability; its CVE record was published on July 9, 2026. Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, under certain non-default configurations, processing of PDF uploads could be exploited to obtain RCE on the server. This issue is patched in 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5.
When was the CVE record for CVE-2026-55420 published?
The CVE record for CVE-2026-55420 was published on July 9, 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 July 14, 2026; the record at its source may have been updated since.
Is CVE-2026-55420 actively exploited?
CVE-2026-55420 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (47th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-55420?
CVE-2026-55420 has a CVSS v3 base score of 8.1 (NVD).
How do I remediate CVE-2026-55420?
The CVE record for CVE-2026-55420 names the fix: "This issue is patched in 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5."

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