CVE-2026-72721

MEDIUMPre-NVD 5.35.3
EchelonGraph scoreMEDIUM confidence

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

This medium-severity CVE scores 5.3 under a secondary CVSS source (NVD's own analysis pending). 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 a secondary CVSS source
Sources: EPSS, a secondary CVSS source

Also known asEUVD-2026-55657 (ENISA EUVD)Source: ENISA EUVD

5.3EG
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: 5.3Exploit: 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, Onebox::DomainChecker.is_blocked? compares hostnames and SiteSetting.blocked_onebox_domains entries case-sensitively, allowing an attacker to bypass configured Onebox domain restrictions by changing character casing in a redirect target hostname. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.

CVSS v3
5.3
EG Score
5.3MEDIUMmedium confidence
EG Risk
39
EG Risk 39/100

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)
Severity53% × 45%
Impact severity (EG Severity): CVSS 5.3 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.
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: The CVE record names the fixed release. 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
47th
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 (5.3): severity, escalated by confirmed exploitation. This CVE's 5.3 is its impact severity (EG Severity), not escalated.

EG Severity
5.3 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).

The CVE record names the fixed release. 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 10, 2026

Last Modified

September 8, 2026

Advisory Details (9)

Auto-updated Aug 10, 2026
Fix named in the CVE record. Sources: github_pr, github, github_commit.
GitHub advisoryMentions a patch (unverified)

Onebox Domain Blocklist Bypass via Case-Sensitive Comparison · Advisory · discourse/discourse · GitHub

https://github.com/discourse/discourse/security/advisories/GHSA-3x7x-24rq-h5j6
GitHub pull request

Security fixes for release/2026.6

Fix merged in discourse/discourse PR #42094 on 2026-07-28 — awaiting tagged release

https://github.com/discourse/discourse/pull/42094
GitHub pull request

Security fixes for release/2026.5

Fix merged in discourse/discourse PR #42093 on 2026-07-28 — awaiting tagged release

https://github.com/discourse/discourse/pull/42093
GitHub pull request

Security fixes for release/2026.1

Fix merged in discourse/discourse PR #42092 on 2026-07-28 — awaiting tagged release

https://github.com/discourse/discourse/pull/42092
GitHub pull request

Security fixes for main

Fix merged in discourse/discourse PR #42091 on 2026-07-28 — awaiting tagged release

https://github.com/discourse/discourse/pull/42091
GitHub commit

commit f503971d311b (discourse/discourse)

Fix landed in discourse/discourse commit f503971d311b — awaiting tagged release

https://github.com/discourse/discourse/commit/f503971d311b7b0dfdb751ee8cfd67e8cb99f5c5
GitHub commit

commit caa615c371b1 (discourse/discourse)

Fix landed in discourse/discourse commit caa615c371b1 — awaiting tagged release

https://github.com/discourse/discourse/commit/caa615c371b1696982ee11ac8f3558f0f8ced584
GitHub commit

commit c2eb6b0e5597 (discourse/discourse)

Fix landed in discourse/discourse commit c2eb6b0e5597 — awaiting tagged release

https://github.com/discourse/discourse/commit/c2eb6b0e5597d6f28f4be739b83300bc9c69e3cd
GitHub commit

commit a3e10759fef4 (discourse/discourse)

Fix landed in discourse/discourse commit a3e10759fef4 — awaiting tagged release

https://github.com/discourse/discourse/commit/a3e10759fef47f03d450649bb51d9e84f4c68b8f

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 40× 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 98 of 127 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. 2 repeat rows among the latest 100 are merged into the row they repeat. The 29 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  2. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  3. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  4. 2026-10-30 06:55 UTCOSV refresh
  5. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  6. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  7. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  8. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  9. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  10. 2026-10-25 14:06 UTCEG score recompute
  11. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  12. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  13. 2026-10-22 19:22 UTCEG score recompute
  14. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  15. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  16. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  17. 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  18. 2026-10-18 03:15 UTCEG score recompute
  19. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  20. 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  21. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  22. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  23. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  24. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  25. 2026-10-12 15:41 UTCEG score recompute
Show 73 more
  1. 2026-10-11 19:27 UTCEG score recompute
  2. 2026-10-11 16:42 UTCEG score recompute
  3. 2026-10-11 14:02 UTCEG score recompute
  4. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  5. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  6. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  7. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  8. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  9. 2026-10-06 18:21 UTCEG score recompute
  10. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  11. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  12. 2026-10-05 07:48 UTCEG score recompute
  13. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  14. 2026-10-04 04:26 UTCEG score recompute
  15. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  16. 2026-10-02 09:19 UTCEG score recompute
  17. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  18. 2026-09-30 22:36 UTCEG score recompute
  19. 2026-09-29 05:22 UTCEG score recompute
  20. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  21. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  22. 2026-09-27 12:45 UTCEG score recompute
  23. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  24. 2026-09-25 04:01 UTCEG score recompute
  25. 2026-09-23 21:10 UTCEG score recompute
  26. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  27. 2026-09-22 15:23 UTCEG score recompute
  28. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  29. 2026-09-21 13:05 UTCEG score recompute
  30. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  31. 2026-09-20 10:48 UTCEG score recompute
  32. 2026-09-19 05:19 UTCEG score recompute
  33. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  34. 2026-09-18 03:02 UTCEG score recompute
  35. 2026-09-17 00:45 UTCEG score recompute
  36. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  37. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  38. 2026-09-15 13:46 UTCEG score recompute
  39. 2026-09-15 03:12 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  40. 2026-09-14 11:09 UTCEG score recompute
  41. 2026-09-13 08:53 UTCEG score recompute
  42. 2026-09-12 15:02 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  43. 2026-09-12 06:36 UTCEG score recompute
  44. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  45. 2026-09-11 04:18 UTCEG score recompute
  46. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  47. 2026-09-10 02:01 UTCEG score recompute
  48. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  49. 2026-09-07 17:17 UTCEG score recompute
  50. 2026-09-06 13:48 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  51. 2026-09-06 12:57 UTCEG score recompute
  52. 2026-09-05 10:40 UTCEG score recompute
  53. 2026-09-04 08:22 UTCEG score recompute
  54. 2026-09-04 05:07 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  55. 2026-09-03 03:07 UTCEG score recompute
  56. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  57. 2026-09-02 00:45 UTCEG score recompute
  58. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  59. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  60. 2026-08-31 22:11 UTCEG score recompute
  61. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  62. 2026-08-30 12:15 UTCEG score recompute
  63. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  64. 2026-08-29 09:58 UTCEG score recompute
  65. 2026-08-28 21:42 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  66. 2026-08-28 06:21 UTCEG score recompute
  67. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  68. 2026-08-27 03:59 UTCEG score recompute
  69. 2026-08-26 14:47 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  70. 2026-08-26 01:41 UTCEG score recompute
  71. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  72. 2026-08-24 23:25 UTCEG score recompute
  73. 2026-08-23 21:08 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-72721?
CVE-2026-72721 is a medium-severity vulnerability; its CVE record was published on August 10, 2026. Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, Onebox::DomainChecker.is_blocked? compares hostnames and SiteSetting.blocked_onebox_domains entries case-sensitively, allowing an attacker to bypass configured Onebox domain restrictions by…
When was the CVE record for CVE-2026-72721 published?
The CVE record for CVE-2026-72721 was published on August 10, 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 8, 2026; the record at its source may have been updated since.
Is CVE-2026-72721 actively exploited?
CVE-2026-72721 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-2026-72721?
CVE-2026-72721 has a CVSS base score of 5.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-72721?
The CVE record for CVE-2026-72721 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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