CVE-2026-42897

CRITICALPre-NVD 8.19.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2026-05-15), indicating real-world exploitation has been confirmed by US federal agencies. the CNA's CVSS baseline 8.1 retained for reference (NVD's own analysis pending). Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, cna:microsoft, epss, ghsa
Trending — 5 sources updated this weekExploited in the wild
9.0EG
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS PROB: 71%CVSS: 8.1Exploit: cisa kev · ssvc active · epss top5pct · epss high · public exploitExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.

CVSS v3
8.1
EG Score
9.0(high)
EG Risk
81(Attend)
EG Risk 81/100SSVC: Attend

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
Severity90% × 45%
Exploitation100% × 40%
Automatability0% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
71%
EPSS %ILE
99%
KEV
⚠ Exploited

Published

May 14, 2026

Last Modified

August 10, 2026

Advisory Details (1)

Auto-updated May 14, 2026
Patch available. Sources: microsoft.
microsoft Patch Available

Security Update Guide - Microsoft Security Response Center

Security Update Guide - Microsoft Security Response Center. Patch available via Microsoft Security Update

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42897

Vendor Advisories for CVE-2026-42897(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 95× in last 7d / 387× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

Showing the most recent 100 of 1,279 total refreshes for this CVE.

  1. 2026-09-05 04:33 UTCVendor advisory
  2. 2026-09-05 04:33 UTCGHSA enrichment
  3. 2026-09-05 00:27 UTCVendor advisory
  4. 2026-09-05 00:27 UTCGHSA enrichment
  5. 2026-09-04 20:22 UTCVendor advisory
  6. 2026-09-04 20:22 UTCGHSA enrichment
  7. 2026-09-04 17:38 UTCCISA KEV update
  8. 2026-09-04 16:16 UTCVendor advisory
  9. 2026-09-04 16:16 UTCGHSA enrichment
  10. 2026-09-04 12:12 UTCVendor advisory
  11. 2026-09-04 12:12 UTCGHSA enrichment
  12. 2026-09-04 08:07 UTCEG score recompute
  13. 2026-09-04 08:07 UTCVendor advisory
  14. 2026-09-04 08:07 UTCGHSA enrichment
  15. 2026-09-04 05:06 UTCEPSS rescore
  16. 2026-09-04 04:00 UTCVendor advisory
  17. 2026-09-04 04:00 UTCGHSA enrichment
  18. 2026-09-03 23:56 UTCVendor advisory
  19. 2026-09-03 23:56 UTCGHSA enrichment
  20. 2026-09-03 19:51 UTCVendor advisory
  21. 2026-09-03 19:51 UTCGHSA enrichment
  22. 2026-09-03 15:45 UTCVendor advisory
  23. 2026-09-03 15:45 UTCGHSA enrichment
  24. 2026-09-03 11:39 UTCVendor advisory
  25. 2026-09-03 11:39 UTCGHSA enrichment
Show 75 more
  1. 2026-09-03 07:32 UTCVendor advisory
  2. 2026-09-03 07:32 UTCGHSA enrichment
  3. 2026-09-03 03:26 UTCVendor advisory
  4. 2026-09-03 03:26 UTCGHSA enrichment
  5. 2026-09-02 23:21 UTCVendor advisory
  6. 2026-09-02 23:21 UTCGHSA enrichment
  7. 2026-09-02 19:14 UTCVendor advisory
  8. 2026-09-02 19:14 UTCGHSA enrichment
  9. 2026-09-02 17:33 UTCCISA KEV update
  10. 2026-09-02 15:08 UTCEG score recompute
  11. 2026-09-02 15:08 UTCVendor advisory
  12. 2026-09-02 15:08 UTCGHSA enrichment
  13. 2026-09-02 14:12 UTCEPSS rescore
  14. 2026-09-02 11:01 UTCVendor advisory
  15. 2026-09-02 11:00 UTCGHSA enrichment
  16. 2026-09-02 06:55 UTCVendor advisory
  17. 2026-09-02 06:55 UTCGHSA enrichment
  18. 2026-09-02 02:50 UTCVendor advisory
  19. 2026-09-02 02:50 UTCGHSA enrichment
  20. 2026-09-01 22:44 UTCVendor advisory
  21. 2026-09-01 22:44 UTCGHSA enrichment
  22. 2026-09-01 18:39 UTCVendor advisory
  23. 2026-09-01 18:39 UTCGHSA enrichment
  24. 2026-09-01 14:33 UTCEG score recompute
  25. 2026-09-01 14:33 UTCVendor advisory
  26. 2026-09-01 14:33 UTCGHSA enrichment
  27. 2026-09-01 13:54 UTCEPSS rescore
  28. 2026-09-01 10:26 UTCVendor advisory
  29. 2026-09-01 10:25 UTCGHSA enrichment
  30. 2026-09-01 06:20 UTCVendor advisory
  31. 2026-09-01 06:19 UTCGHSA enrichment
  32. 2026-09-01 02:13 UTCVendor advisory
  33. 2026-09-01 02:13 UTCGHSA enrichment
  34. 2026-08-31 22:08 UTCVendor advisory
  35. 2026-08-31 22:07 UTCGHSA enrichment
  36. 2026-08-31 18:02 UTCVendor advisory
  37. 2026-08-31 18:02 UTCGHSA enrichment
  38. 2026-08-31 14:19 UTCCISA KEV update
  39. 2026-08-31 13:57 UTCVendor advisory
  40. 2026-08-31 13:56 UTCGHSA enrichment
  41. 2026-08-31 09:49 UTCVendor advisory
  42. 2026-08-31 09:49 UTCGHSA enrichment
  43. 2026-08-31 05:44 UTCVendor advisory
  44. 2026-08-31 05:44 UTCGHSA enrichment
  45. 2026-08-31 01:40 UTCVendor advisory
  46. 2026-08-31 01:40 UTCGHSA enrichment
  47. 2026-08-30 21:35 UTCEG score recompute
  48. 2026-08-30 21:35 UTCVendor advisory
  49. 2026-08-30 21:35 UTCGHSA enrichment
  50. 2026-08-30 19:17 UTCEPSS rescore
  51. 2026-08-30 17:30 UTCVendor advisory
  52. 2026-08-30 17:30 UTCGHSA enrichment
  53. 2026-08-30 13:25 UTCVendor advisory
  54. 2026-08-30 13:25 UTCGHSA enrichment
  55. 2026-08-30 09:20 UTCVendor advisory
  56. 2026-08-30 09:20 UTCGHSA enrichment
  57. 2026-08-30 05:14 UTCEG score recompute
  58. 2026-08-30 05:14 UTCVendor advisory
  59. 2026-08-30 05:14 UTCGHSA enrichment
  60. 2026-08-30 01:22 UTCEPSS rescore
  61. 2026-08-30 01:09 UTCVendor advisory
  62. 2026-08-30 01:09 UTCGHSA enrichment
  63. 2026-08-29 21:04 UTCVendor advisory
  64. 2026-08-29 21:03 UTCGHSA enrichment
  65. 2026-08-29 16:56 UTCVendor advisory
  66. 2026-08-29 16:56 UTCGHSA enrichment
  67. 2026-08-29 12:51 UTCVendor advisory
  68. 2026-08-29 12:51 UTCGHSA enrichment
  69. 2026-08-29 08:46 UTCVendor advisory
  70. 2026-08-29 08:45 UTCGHSA enrichment
  71. 2026-08-29 04:39 UTCVendor advisory
  72. 2026-08-29 04:39 UTCGHSA enrichment
  73. 2026-08-29 00:33 UTCEG score recompute
  74. 2026-08-29 00:33 UTCVendor advisory
  75. 2026-08-29 00:33 UTCGHSA enrichment

Publicly available exploits

(1 reference)

Working exploit code is in the public domain (1 GitHub PoC). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCatiilla/CVE-2026-42897
    First seen May 15, 2026

    CVE-2026-42897 - Exchange Health Checker blind spot: outbound IIS URL Rewrite rules silently ignored, making EOMT mitigations invisible in diagnostic reports.

    Open source ↗

Related CVEs(same vendor + same CWE)

Frequently asked(6)

What is CVE-2026-42897?
CVE-2026-42897 is a critical vulnerability published on May 14, 2026. Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.
When was CVE-2026-42897 disclosed?
CVE-2026-42897 was first published in the National Vulnerability Database on May 14, 2026, with the most recent update on August 10, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-42897 actively exploited?
Yes. CISA added CVE-2026-42897 to the Known Exploited Vulnerabilities catalog on May 15, 2026, affecting Microsoft Microsoft. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2026-42897?
CVE-2026-42897 has a CVSS v4.0 base score of 8.1 (CNA self-assessment; NVD's own analysis pending). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
Which products are affected by CVE-2026-42897?
CVE-2026-42897 affects Microsoft Microsoft. The full affected-products list, including version ranges and fixed versions, is shown in the Affected Packages section of this page.
How do I remediate CVE-2026-42897?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-42897, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-42897

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