CVE-2026-55674

CRITICALPre-NVD 9.39.3
EchelonGraph scoreMEDIUM confidence

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

This critical-severity CVE scores 9.3 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-2026-60236 (ENISA EUVD)Source: ENISA EUVD

9.3EG
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: 9.3Exploit: None knownExposed services: Not assessed

The CVE record names the fixed release — apply it.

Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, an unauthenticated attacker could send a single request with a crafted color_scheme_id (or dark_scheme_id) cookie to inject arbitrary HTML into a Discourse page. Because the cookie value was rendered into a color scheme tag without escaping, the attacker could break out of the attribute and inject a tag that bypassed Discourse's nonce-based Content Security Policy, resulting in arbitrary JavaScript execution in visitors' browsers. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.

CVSS v3
9.3
EG Score
9.3CRITICALmedium confidence
EG Risk
42
EG Risk 42/100

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)
Severity93% × 45%
Impact severity (EG Severity): CVSS 9.3 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.
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
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 (9.3): severity, escalated by confirmed exploitation. This CVE's 9.3 is its impact severity (EG Severity), not escalated.

EG Severity
9.3 CRITICALCVSS-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 2026-10-29). 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; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

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

August 17, 2026

Last Modified

September 18, 2026

Advisory Details (1)

Auto-updated Oct 3, 2026
Fix named in the CVE record. Sources: github.
GitHub advisoryMentions a patch (unverified)

Cache poisoning/XSS via color scheme cookies · Advisory · discourse/discourse · GitHub

https://github.com/discourse/discourse/security/advisories/GHSA-qx4v-rg4v-pm2g

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 15× in last 7d / 58× 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 139 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 39 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  2. 2026-10-30 12:26 UTCEG score recompute
  3. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  4. 2026-10-29 12:47 UTCEG score recompute
  5. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  6. 2026-10-28 13:08 UTCEG score recompute
  7. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  8. 2026-10-27 13:25 UTCEG score recompute
  9. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  10. 2026-10-26 13:18 UTCEG score recompute
  11. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  12. 2026-10-25 14:18 UTCEG score recompute
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  14. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  15. 2026-10-24 13:44 UTCEG score recompute
  16. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  17. 2026-10-23 14:04 UTCEG score recompute
  18. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.6% · 47th percentile
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  20. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  21. 2026-10-21 14:28 UTCEG score recompute
  22. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  23. 2026-10-20 14:36 UTCEG score recompute
  24. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  25. 2026-10-19 13:41 UTCEG score recompute
Show 75 more
  1. 2026-10-18 03:30 UTCEG score recompute
  2. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  3. 2026-10-17 14:07 UTCEG score recompute
  4. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  5. 2026-10-16 14:26 UTCEG score recompute
  6. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  7. 2026-10-15 14:45 UTCEG score recompute
  8. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  9. 2026-10-14 09:17 UTCEG score recompute
  10. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  11. 2026-10-13 06:33 UTCEG score recompute
  12. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  13. 2026-10-12 15:55 UTCEG score recompute
  14. 2026-10-11 19:38 UTCEG score recompute
  15. 2026-10-11 16:54 UTCEG score recompute
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  17. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  18. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  19. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  20. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  21. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  22. 2026-10-06 17:10 UTCEG score recompute
  23. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  24. 2026-10-06 09:03 UTCEG score recompute
  25. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  26. 2026-10-05 01:57 UTCEG score recompute
  27. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  28. 2026-10-03 17:48 UTCEG score recompute
  29. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  30. 2026-10-02 19:36 UTCEG score recompute
  31. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  32. 2026-10-02 01:34 UTCEG score recompute
  33. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  34. 2026-09-30 20:52 UTCEG score recompute
  35. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  36. 2026-09-30 10:01 UTCEG score recompute
  37. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  38. 2026-09-28 21:59 UTCEG score recompute
  39. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  40. 2026-09-27 16:28 UTCEG score recompute
  41. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  42. 2026-09-27 08:17 UTCEG score recompute
  43. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  44. 2026-09-24 16:14 UTCEG score recompute
  45. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  46. 2026-09-23 20:27 UTCEG score recompute
  47. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  48. 2026-09-22 20:41 UTCEG score recompute
  49. 2026-09-21 22:28 UTCEG score recompute
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  51. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  52. 2026-09-19 16:08 UTCEG score recompute
  53. 2026-09-18 20:24 UTCEG score recompute
  54. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.4% · 32nd percentile
  55. 2026-09-17 21:56 UTCEG score recompute
  56. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.4% · 29th percentile
  57. 2026-09-16 15:17 UTCEG score recompute
  58. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.4% · 29th percentile
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  60. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.4% · 29th percentile
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  62. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  63. 2026-09-13 19:29 UTCEG score recompute
  64. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  65. 2026-09-12 16:38 UTCEG score recompute
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  67. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  68. 2026-09-11 13:19 UTCEG score recompute
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  70. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.4% · 28th percentile
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  74. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  75. 2026-09-06 14:47 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-55674?
CVE-2026-55674 is a critical-severity vulnerability; its CVE record was published on August 17, 2026. Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, an unauthenticated attacker could send a single request with a crafted colorschemeid (or darkschemeid) cookie to inject arbitrary HTML into a Discourse page. Because the cookie value was rendered…
When was the CVE record for CVE-2026-55674 published?
The CVE record for CVE-2026-55674 was published on August 17, 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 18, 2026; the record at its source may have been updated since.
Is CVE-2026-55674 actively exploited?
CVE-2026-55674 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-2026-55674?
CVE-2026-55674 has a CVSS base score of 9.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-55674?
The CVE record for CVE-2026-55674 names the fix: "This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0."

Dependency Blast Radius

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