CVE-2026-91159

HIGHPre-NVD 7.77.7
EchelonGraph scoreMEDIUM confidence

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

This high-severity CVE scores 7.7 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4% (35th 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-2026-101299 (ENISA EUVD)Source: ENISA EUVD

7.7EG
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: 0.4%CVSS: 7.7Exploit: None knownExposed services: Not assessed

The CVE record names the fixed release — apply it.

Discourse is an open-source discussion platform. Prior to 2026.9.0, 2026.8.1, 2026.7.3, and 2026.1.9, oEmbed processing treated an entire attacker-controlled HTML fragment as trusted when the fragment contained an iframe whose source matched the configured allowlist. A user with posting permission who controlled a public webpage and its oEmbed response could combine an allowlisted iframe with unrelated sibling HTML or CSS, causing stored visual overlays or other styled content to appear in post content and enabling misleading or fraudulent user interfaces. Exploitation requires a posting account, control of the fetched webpage and oEmbed response, and an allowlisted iframe source. The issue affects content integrity but does not expose restricted data, disrupt availability, or require interaction with Discourse Content Security Policy. This issue is fixed in versions 2026.9.0, 2026.8.1, 2026.7.3, and 2026.1.9.

CVSS v3
7.7
EG Score
7.7HIGHmedium confidence
EG Risk
35
EG Risk 35/100

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)
Severity77% × 45%
Impact severity (EG Severity): CVSS 7.7 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.4% × 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
0.4%
EPSS %ILE
35th
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 (7.7): severity, escalated by confirmed exploitation. This CVE's 7.7 is its impact severity (EG Severity), not escalated.

EG Severity
7.7 HIGHCVSS-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
0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-27). 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

October 14, 2026

Last Modified

October 20, 2026

Advisory Details (5)

Auto-updated Oct 14, 2026
Fix named in the CVE record. Sources: github, github_commit.
GitHub commit

commit ed6f83f123d1 (discourse/discourse)

Fix landed in discourse/discourse commit ed6f83f123d1 — awaiting tagged release

https://github.com/discourse/discourse/commit/ed6f83f123d1a4c6c6c7e64c8a2233e3cb6a28d7
GitHub commit

commit dde8bc4fb620 (discourse/discourse)

Fix landed in discourse/discourse commit dde8bc4fb620 — awaiting tagged release

https://github.com/discourse/discourse/commit/dde8bc4fb6200139f5eff7e100b0f3e829d37ab3
GitHub commit

commit 3fc2bad6cdca (discourse/discourse)

Fix landed in discourse/discourse commit 3fc2bad6cdca — awaiting tagged release

https://github.com/discourse/discourse/commit/3fc2bad6cdca47b00958330d1ee612aa141b039a
GitHub commit

commit 0953b31f5c29 (discourse/discourse)

Fix landed in discourse/discourse commit 0953b31f5c29 — awaiting tagged release

https://github.com/discourse/discourse/commit/0953b31f5c2949d7d6ab5f6dc4c5e2f1b8bf0b22
GitHub advisoryMentions a patch (unverified)

Stored oEmbed HTML injection via allowed iframe · Advisory · discourse/discourse · GitHub

https://github.com/discourse/discourse/security/advisories/GHSA-f9jx-vv33-4282

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 27× 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.

  1. 2026-11-02 16:46 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  2. 2026-11-01 16:36 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  3. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  4. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  5. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  6. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  7. 2026-10-27 19:39 UTCEG score recompute
  8. 2026-10-27 16:33 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  9. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  10. 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  11. 2026-10-25 13:51 UTCEG score recompute
  12. 2026-10-24 16:34 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  13. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  14. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  15. 2026-10-21 16:34 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  16. 2026-10-20 16:34 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  17. 2026-10-20 02:26 UTCEG score recompute
  18. 2026-10-20 01:53 UTCEG score recompute
  19. 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  20. 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  21. 2026-10-18 03:00 UTCEG score recompute
  22. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  23. 2026-10-16 16:45 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  24. 2026-10-15 16:33 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  25. 2026-10-14 17:13 UTCEG score recompute
Show 2 more
  1. 2026-10-14 15:40 UTCEG score recomputeFirst assessed: 7.7 HIGH
  2. 2026-10-14 15:39 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-91159?
CVE-2026-91159 is a high-severity vulnerability; its CVE record was published on October 14, 2026. Discourse is an open-source discussion platform. Prior to 2026.9.0, 2026.8.1, 2026.7.3, and 2026.1.9, oEmbed processing treated an entire attacker-controlled HTML fragment as trusted when the fragment contained an iframe whose source matched the configured allowlist. A user with posting permission…
When was the CVE record for CVE-2026-91159 published?
The CVE record for CVE-2026-91159 was published on October 14, 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 October 20, 2026; the record at its source may have been updated since.
Is CVE-2026-91159 actively exploited?
CVE-2026-91159 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (35th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-91159?
CVE-2026-91159 has a CVSS base score of 7.7 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-91159?
The CVE record for CVE-2026-91159 names the fix: "This issue is fixed in versions 2026.9.0, 2026.8.1, 2026.7.3, and 2026.1.9."

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-91159

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