CVE-2026-55850

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: 0.5% (44th 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
5.3EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 5.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Element Web is a Matrix web client built using the Matrix React SDK. Prior to 1.12.22, EmbeddedPage in apps/web/src/components/structures/EmbeddedPage.tsx renders homeserver-supplied homepage content through dangerouslySetInnerHTML without passing it through sanitizedHtmlNode. A malicious homeserver can provide crafted HTML that Element Web renders on the homepage; the content security policy prevents JavaScript but not phishing HTML. This issue is fixed in version 1.12.22.

CVSS v3
5.3
EG Score
5.3MEDIUMmedium confidence
EG Risk
24
EG Risk 24/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed (value × EchelonGraph’s weight)
Severity53% × 45%
The EG Score, 5.3 of 10.
Exploitation0.5% × 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: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.5%
EPSS %ILE
44th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

A fix is available. 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.

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

August 21, 2026

Last Modified

September 30, 2026

Advisory Details (4)

Auto-updated Aug 21, 2026
Patch available. Sources: github_commit, github_release, github.
Web page

CVE-2026-55850: Phishing via HTML Injection in Element Web

https://www.machinespirits.com/advisory/563a17
GitHub release Patch Available

v1.12.22

Patch available: element-hq/element-web v1.12.22

https://github.com/element-hq/element-web/releases/tag/v1.12.22
GitHub commit

commit 7949980a7e3c (element-hq/element-web)

Fix landed in element-hq/element-web commit 7949980a7e3c — awaiting tagged release

https://github.com/element-hq/element-web/commit/7949980a7e3c7e397d7afe899ef1b0563c417b0e
GitHub advisoryMentions a patch (unverified)

A malicious homeserver can inject HTML in Element Web using its homepage · Advisory · element-hq/element-web · GitHub

https://github.com/element-hq/element-web/security/advisories/GHSA-wrcp-5v3v-3j6v

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 51× 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. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  2. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  3. 2026-10-12 15:55 UTCEG score recompute
  4. 2026-10-11 19:38 UTCEG score recompute
  5. 2026-10-11 16:53 UTCEG score recompute
  6. 2026-10-11 14:16 UTCEG score recompute
  7. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  9. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  10. 2026-10-09 05:47 UTCEG score recompute
  11. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  12. 2026-10-08 04:55 UTCEG score recompute
  13. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  14. 2026-10-06 19:21 UTCEG score recompute
  15. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  16. 2026-10-05 20:01 UTCEG score recompute
  17. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  18. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  19. 2026-10-03 20:14 UTCEG score recompute
  20. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  21. 2026-10-02 20:59 UTCEG score recompute
  22. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  23. 2026-10-01 21:24 UTCEG score recompute
  24. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  25. 2026-09-30 20:04 UTCEG score recompute
Show 67 more
  1. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  2. 2026-09-30 07:52 UTCEG score recompute
  3. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  4. 2026-09-29 01:47 UTCEG score recompute
  5. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  6. 2026-09-28 01:59 UTCEG score recompute
  7. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  8. 2026-09-27 02:28 UTCEG score recompute
  9. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  10. 2026-09-24 19:16 UTCEG score recompute
  11. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  12. 2026-09-23 20:02 UTCEG score recompute
  13. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  14. 2026-09-22 20:17 UTCEG score recompute
  15. 2026-09-20 21:49 UTCEG score recompute
  16. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  17. 2026-09-19 22:34 UTCEG score recompute
  18. 2026-09-18 23:19 UTCEG score recompute
  19. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  20. 2026-09-18 00:06 UTCEG score recompute
  21. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  22. 2026-09-17 00:28 UTCEG score recompute
  23. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  24. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  25. 2026-09-16 01:14 UTCEG score recompute
  26. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  27. 2026-09-14 02:45 UTCEG score recompute
  28. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  29. 2026-09-13 03:32 UTCEG score recompute
  30. 2026-09-12 04:18 UTCEG score recompute
  31. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  32. 2026-09-11 05:04 UTCEG score recompute
  33. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  34. 2026-09-09 06:36 UTCEG score recompute
  35. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  36. 2026-09-07 08:10 UTCEG score recompute
  37. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  38. 2026-09-06 08:52 UTCEG score recompute
  39. 2026-09-05 09:38 UTCEG score recompute
  40. 2026-09-04 10:25 UTCEG score recompute
  41. 2026-09-04 05:07 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  42. 2026-09-03 11:11 UTCEG score recompute
  43. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  44. 2026-09-02 11:58 UTCEG score recompute
  45. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  46. 2026-09-01 12:42 UTCEG score recompute
  47. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  48. 2026-08-31 13:08 UTCEG score recompute
  49. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  50. 2026-08-30 13:37 UTCEG score recompute
  51. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  52. 2026-08-29 14:21 UTCEG score recompute
  53. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  54. 2026-08-27 15:48 UTCEG score recompute
  55. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  56. 2026-08-26 16:31 UTCEG score recompute
  57. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  58. 2026-08-25 17:17 UTCEG score recompute
  59. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  60. 2026-08-24 18:04 UTCEG score recompute
  61. 2026-08-23 18:50 UTCEG score recompute
  62. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  63. 2026-08-21 20:23 UTCEG score recompute
  64. 2026-08-21 19:59 UTCEG score recompute
  65. 2026-08-21 19:21 UTCEG score recompute
  66. 2026-08-21 18:49 UTCEG score recomputeFirst assessed: 5.3 MEDIUM
  67. 2026-08-21 18:49 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-55850?
CVE-2026-55850 is a medium-severity vulnerability; its CVE record was published on August 21, 2026. Element Web is a Matrix web client built using the Matrix React SDK. Prior to 1.12.22, EmbeddedPage in apps/web/src/components/structures/EmbeddedPage.tsx renders homeserver-supplied homepage content through dangerouslySetInnerHTML without passing it through sanitizedHtmlNode. A malicious…
When was the CVE record for CVE-2026-55850 published?
The CVE record for CVE-2026-55850 was published on August 21, 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 30, 2026; the record at its source may have been updated since.
Is CVE-2026-55850 actively exploited?
CVE-2026-55850 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (44th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-55850?
CVE-2026-55850 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-2026-55850?
A fix for CVE-2026-55850 is available: update to the fixed version the vendor names in its advisory.

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