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CVE-2026-21258

Improper input validation in Microsoft Office Excel allows an unauthorized attacker to disclose information locally.
Lifecycle PUBLISHED1 preserved revisionFact urn:baitaphish:canonical-cve-fact-revision:v2:c51b78f19676f1a67ebff6e452076daeb22b04d443a30c487e56bfbd3459a35a
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
2

Preserved source conflicts

No provider value was silently selected as the winner.

affected · 8 assertions

{"product":"Office Online Server","vendor":"Microsoft","versions":[{"lessThan":"16.0.10417.20097","status":"affected","version":"16.0.0.0","versionType":"custom"}]}

  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/affected/7

{"product":"Microsoft Office LTSC for Mac 2024","vendor":"Microsoft","versions":[{"lessThan":"16.106.26020821","status":"affected","version":"16.0.0","versionType":"custom"}]}

  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/affected/6

{"platforms":["32-bit Systems","x64-based Systems"],"product":"Microsoft Excel 2016","vendor":"Microsoft","versions":[{"lessThan":"16.0.5539.1002","status":"affected","version":"16.0.0.0","versionType":"custom"}]}

  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/affected/1

{"platforms":["32-bit Systems","x64-based Systems"],"product":"Microsoft Office 2019","vendor":"Microsoft","versions":[{"lessThan":"https://aka.ms/OfficeSecurityReleases","status":"affected","version":"19.0.0","versionType":"custom"}]}

  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/affected/2

{"product":"Microsoft Office LTSC for Mac 2021","vendor":"Microsoft","versions":[{"lessThan":"16.106.26020821","status":"affected","version":"16.0.1","versionType":"custom"}]}

  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/affected/5

{"platforms":["32-bit Systems","x64-based Systems"],"product":"Microsoft Office LTSC 2024","vendor":"Microsoft","versions":[{"lessThan":"https://aka.ms/OfficeSecurityReleases","status":"affected","version":"16.0.0","versionType":"custom"}]}

  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/affected/4

{"platforms":["32-bit Systems","x64-based Systems"],"product":"Microsoft Office LTSC 2021","vendor":"Microsoft","versions":[{"lessThan":"https://aka.ms/OfficeSecurityReleases","status":"affected","version":"16.0.1","versionType":"custom"}]}

  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/affected/3

{"platforms":["32-bit Systems","x64-based Systems"],"product":"Microsoft 365 Apps for Enterprise","vendor":"Microsoft","versions":[{"lessThan":"https://aka.ms/OfficeSecurityReleases","status":"affected","version":"16.0.1","versionType":"custom"}]}

  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/affected/0
cwe · 2 assertions

{"cweId":"CWE-20","description":"CWE-20: Improper Input Validation","lang":"en-US","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/problemTypes/0/descriptions/0

{"cweId":"CWE-125","description":"CWE-125: Out-of-bounds Read","lang":"en-US","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/problemTypes/0/descriptions/1

Affected products and versions

8 source assertions
{"product":"Office Online Server","vendor":"Microsoft","versions":[{"lessThan":"16.0.10417.20097","status":"affected","version":"16.0.0.0","versionType":"custom"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/affected/7
{"product":"Microsoft Office LTSC for Mac 2024","vendor":"Microsoft","versions":[{"lessThan":"16.106.26020821","status":"affected","version":"16.0.0","versionType":"custom"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/affected/6
{"platforms":["32-bit Systems","x64-based Systems"],"product":"Microsoft Excel 2016","vendor":"Microsoft","versions":[{"lessThan":"16.0.5539.1002","status":"affected","version":"16.0.0.0","versionType":"custom"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/affected/1
{"platforms":["32-bit Systems","x64-based Systems"],"product":"Microsoft Office 2019","vendor":"Microsoft","versions":[{"lessThan":"https://aka.ms/OfficeSecurityReleases","status":"affected","version":"19.0.0","versionType":"custom"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/affected/2
{"product":"Microsoft Office LTSC for Mac 2021","vendor":"Microsoft","versions":[{"lessThan":"16.106.26020821","status":"affected","version":"16.0.1","versionType":"custom"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/affected/5
{"platforms":["32-bit Systems","x64-based Systems"],"product":"Microsoft Office LTSC 2024","vendor":"Microsoft","versions":[{"lessThan":"https://aka.ms/OfficeSecurityReleases","status":"affected","version":"16.0.0","versionType":"custom"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/affected/4
{"platforms":["32-bit Systems","x64-based Systems"],"product":"Microsoft Office LTSC 2021","vendor":"Microsoft","versions":[{"lessThan":"https://aka.ms/OfficeSecurityReleases","status":"affected","version":"16.0.1","versionType":"custom"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/affected/3
{"platforms":["32-bit Systems","x64-based Systems"],"product":"Microsoft 365 Apps for Enterprise","vendor":"Microsoft","versions":[{"lessThan":"https://aka.ms/OfficeSecurityReleases","status":"affected","version":"16.0.1","versionType":"custom"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/affected/0

Provider-owned CVSS observations

1 source assertion
{"metric":{"baseScore":5.5,"baseSeverity":"MEDIUM","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C","version":"3.1"},"metric_type":"cvssV3_1"}
  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/metrics/0/cvssV3_1

CWE assertions

2 source assertions
{"cweId":"CWE-20","description":"CWE-20: Improper Input Validation","lang":"en-US","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/problemTypes/0/descriptions/0
{"cweId":"CWE-125","description":"CWE-125: Out-of-bounds Read","lang":"en-US","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/problemTypes/0/descriptions/1

Source references

1 source assertion
{"name":"Microsoft Excel Information Disclosure Vulnerability","tags":["vendor-advisory","patch"],"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21258"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:fa03f856bd407716e8ab9f63613df546c4c9253a18db3d4e36ed74eae58b0268 · sha256:628a82b5bb5722d0… · /containers/cna/references/0

Attribution and limitations

  • CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →

Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.

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