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.
CVE-2026-72721
“—” 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.
Also known asEUVD-2026-55657 (ENISA EUVD)Source: ENISA EUVD
- Lower severity and no public exploit yet
The CVE record names the fixed release — apply it.
- CVSS v3
- 5.3
- EG Score
- 5.3MEDIUMmedium confidence
- EG Risk
- 39EG 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, 2026Onebox Domain Blocklist Bypass via Case-Sensitive Comparison · Advisory · discourse/discourse · GitHub
https://github.com/discourse/discourse/security/advisories/GHSA-3x7x-24rq-h5j6Security 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/42094Security 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/42093Security 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/42092Security fixes for main
Fix merged in discourse/discourse PR #42091 on 2026-07-28 — awaiting tagged release
https://github.com/discourse/discourse/pull/42091commit f503971d311b (discourse/discourse)
Fix landed in discourse/discourse commit f503971d311b — awaiting tagged release
https://github.com/discourse/discourse/commit/f503971d311b7b0dfdb751ee8cfd67e8cb99f5c5commit caa615c371b1 (discourse/discourse)
Fix landed in discourse/discourse commit caa615c371b1 — awaiting tagged release
https://github.com/discourse/discourse/commit/caa615c371b1696982ee11ac8f3558f0f8ced584commit c2eb6b0e5597 (discourse/discourse)
Fix landed in discourse/discourse commit c2eb6b0e5597 — awaiting tagged release
https://github.com/discourse/discourse/commit/c2eb6b0e5597d6f28f4be739b83300bc9c69e3cdcommit a3e10759fef4 (discourse/discourse)
Fix landed in discourse/discourse commit a3e10759fef4 — awaiting tagged release
https://github.com/discourse/discourse/commit/a3e10759fef47f03d450649bb51d9e84f4c68b8fWeakness 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.
- 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-30 06:55 UTCOSV refresh
- 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-25 14:06 UTCEG score recompute
- 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-22 19:22 UTCEG score recompute
- 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-18 03:15 UTCEG score recompute
- 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-12 15:41 UTCEG score recompute
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- 2026-10-11 19:27 UTCEG score recompute
- 2026-10-11 16:42 UTCEG score recompute
- 2026-10-11 14:02 UTCEG score recompute
- 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-06 18:21 UTCEG score recompute
- 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-05 07:48 UTCEG score recompute
- 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-04 04:26 UTCEG score recompute
- 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-02 09:19 UTCEG score recompute
- 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-09-30 22:36 UTCEG score recompute
- 2026-09-29 05:22 UTCEG score recompute
- 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-09-27 12:45 UTCEG score recompute
- 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-09-25 04:01 UTCEG score recompute
- 2026-09-23 21:10 UTCEG score recompute
- 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-09-22 15:23 UTCEG score recompute
- 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-09-21 13:05 UTCEG score recompute
- 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-09-20 10:48 UTCEG score recompute
- 2026-09-19 05:19 UTCEG score recompute
- 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-09-18 03:02 UTCEG score recompute
- 2026-09-17 00:45 UTCEG score recompute
- 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-09-15 13:46 UTCEG score recompute
- 2026-09-15 03:12 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-09-14 11:09 UTCEG score recompute
- 2026-09-13 08:53 UTCEG score recompute
- 2026-09-12 15:02 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-09-12 06:36 UTCEG score recompute
- 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-09-11 04:18 UTCEG score recompute
- 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.4% · 36th percentile
- 2026-09-10 02:01 UTCEG score recompute
- 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-09-07 17:17 UTCEG score recompute
- 2026-09-06 13:48 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-09-06 12:57 UTCEG score recompute
- 2026-09-05 10:40 UTCEG score recompute
- 2026-09-04 08:22 UTCEG score recompute
- 2026-09-04 05:07 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-09-03 03:07 UTCEG score recompute
- 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-09-02 00:45 UTCEG score recompute
- 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-08-31 22:11 UTCEG score recompute
- 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-08-30 12:15 UTCEG score recompute
- 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-08-29 09:58 UTCEG score recompute
- 2026-08-28 21:42 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-08-28 06:21 UTCEG score recompute
- 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-08-27 03:59 UTCEG score recompute
- 2026-08-26 14:47 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-08-26 01:41 UTCEG score recompute
- 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-08-24 23:25 UTCEG score recompute
- 2026-08-23 21:08 UTCEG score recompute
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Frequently asked(5)
What is CVE-2026-72721?
When was the CVE record for CVE-2026-72721 published?
Is CVE-2026-72721 actively exploited?
What is the CVSS score of CVE-2026-72721?
How do I remediate CVE-2026-72721?
Dependency Blast Radius
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