CVE-2026-26164

high

Published 2026-05-07 · Modified 2026-05-08

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CVSS v3

7.5

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS v4 NEW

—

not yet in upstream

VIR risk

7.5

Description

<p>Improper neutralization of special elements in output used by a downstream component ('injection') in M365 Copilot allows an unauthorized attacker to disclose information over a network.</p>

Predictions

Exploit likelihood

83%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

OS impact

OS	Version	Status	Fixed in
windows		affected

Application impact

Vendor	Product	Versions	Fixed
microsoft	365_copilot_chat	`-`

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26164

CWEs

CWE-74

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.