Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, the Discourse post sanitizer allowed a stored cross-origin iframe to bypass the allowed_iframes prefix policy when the iframe src contained encoded userinfo. The sanitizer validated a decoded form differently from the stored iframe src, allowing the browser to interpret an attacker-controlled host while the allowlist check accepted the encoded URL as an allowed prefix. An authenticated user with posting privileges could persist the iframe in a post and cause attacker-controlled cross-origin content to be rendered. This issue is fixed in versions 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0.
CVE-2026-91134
“—” beside the score: it is equal to the CVSS score beside it.
This medium-severity CVE scores 5.4 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2% (12th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.
Also known asEUVD-2026-86298 (ENISA EUVD)Source: ENISA EUVD
- Lower severity and no public exploit yet
The CVE record names the fixed release — apply it.
- CVSS v3
- 5.4
- EG Score
- 5.4MEDIUMmedium confidence
- EG Risk
- 24EG Risk 24/100
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)Severity54% × 45%Impact severity (EG Severity): CVSS 5.4 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.2% × 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 every mission impact level.Exploitation none (CISA Vulnrichment) · Automatable no (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. - EPSS PROB
- 0.2%
- EPSS %ILE
- 12th
- 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 (5.4): severity, escalated by confirmed exploitation. This CVE's 5.4 is its impact severity (EG Severity), not escalated.
- EG Severity
- 5.4 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
- 0.2% 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 every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade 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 every mission impact level.
The CVE record names the fixed release. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (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)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (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
September 24, 2026
Last Modified
September 29, 2026
Advisory Details (6)
Auto-updated Sep 24, 2026commit fed3a58c4841 (discourse/discourse)
Fix landed in discourse/discourse commit fed3a58c4841 — awaiting tagged release
https://github.com/discourse/discourse/commit/fed3a58c48412ce7207b72a4629ddbc44482cd64commit bac7dd120191 (discourse/discourse)
Fix landed in discourse/discourse commit bac7dd120191 — awaiting tagged release
https://github.com/discourse/discourse/commit/bac7dd1201911851462483271b4567246fa1309dcommit 1304b0c04f87 (discourse/discourse)
Fix landed in discourse/discourse commit 1304b0c04f87 — awaiting tagged release
https://github.com/discourse/discourse/commit/1304b0c04f87534053b0d574ae5a9b9ba13dd590commit 0a8015e6c7a5 (discourse/discourse)
Fix landed in discourse/discourse commit 0a8015e6c7a5 — awaiting tagged release
https://github.com/discourse/discourse/commit/0a8015e6c7a5079981843721494d30c9a91f5415Security fixes for main
Fix merged in discourse/discourse PR #42882 on 2026-08-25 — awaiting tagged release
https://github.com/discourse/discourse/pull/42882Block post iframes whose encoded userinfo bypasses the allowed_iframes allowlist · Advisory · discourse/discourse · GitHub
https://github.com/discourse/discourse/security/advisories/GHSA-54vw-chv3-wjpvWeakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 8× in last 7d / 45× 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.
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. 1 repeat row among the latest 62 is merged into the row it repeats.
- 2026-11-01 16:36 UTCEPSS rescoreEPSS 0.2% · 12th percentile
- 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.2% · 12th percentile
- 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.2% · 12th percentile
- 2026-10-29 22:25 UTCOSV refresh
- 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.2% · 12th percentile
- 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-27 16:33 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-25 13:51 UTCEG score recompute
- 2026-10-24 16:34 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-22 12:30 UTCEG score recompute
- 2026-10-21 16:34 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-20 16:34 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-18 03:00 UTCEG score recompute
- 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-16 16:45 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-15 16:33 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-14 16:34 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.2% · 11th percentile
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- 2026-10-12 14:46 UTCEG score recompute
- 2026-10-11 19:13 UTCEG score recompute
- 2026-10-11 16:30 UTCEG score recompute
- 2026-10-11 13:50 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-11 13:44 UTCEG score recompute
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-10 19:56 UTCEG score recompute
- 2026-10-09 20:08 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-09 18:33 UTCEG score recompute
- 2026-10-08 17:14 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-08 17:00 UTCEG score recompute
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-10-07 14:43 UTCEG score recompute
- 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-10-06 13:20 UTCEG score recompute
- 2026-10-05 17:44 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-10-05 11:57 UTCEG score recompute
- 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-10-04 10:34 UTCEG score recompute
- 2026-10-03 09:06 UTCEG score recompute
- 2026-10-02 07:40 UTCEG score recompute
- 2026-10-01 19:51 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-10-01 06:17 UTCEG score recompute
- 2026-09-30 15:04 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-30 04:54 UTCEG score recompute
- 2026-09-29 03:31 UTCEG score recompute
- 2026-09-29 03:01 UTCEG score recompute
- 2026-09-28 23:25 UTCEG score recompute
- 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-27 22:02 UTCEG score recompute
- 2026-09-27 13:49 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-26 20:38 UTCEG score recompute
- 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-24 17:33 UTCEG score recompute
- 2026-09-24 16:57 UTCEG score recomputeFirst assessed: 5.4 MEDIUM
- 2026-09-24 16:56 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2026-91134?
When was the CVE record for CVE-2026-91134 published?
Is CVE-2026-91134 actively exploited?
What is the CVSS score of CVE-2026-91134?
How do I remediate CVE-2026-91134?
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-91134
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