CVE-2026-26129: Improper neutralization of special elements used in a command ('command injection') in M365 Copilot allows an

This month

HIGH 7.5REMOTEWATCHLISTMITIGATE

CVE-2026-26129 is a high-severity flaw (CVSS 7.5) affecting 365 copilot chat. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Improper neutralization of special elements used in a command ('command injection') in M365 Copilot allows an unauthorized attacker to disclose information over a network.

Why this priority

High severity
Remotely exploitable, no login, no user action
On your watchlist

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.1% (top 34%)
CISA exploited list	No
Weakness	CWE-138
Published	2026-05-07
Last modified	2026-10-26

Publisher (CNA): Microsoft Corporation · Vendor: microsoft

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-07 22:16 UTCPublished CVE record published
2026-10-26 20:10 UTCUpdated Record last modified

microsoft 365 copilot chat MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy 365-copilot-chat || rpm -q 365-copilot-chat || 365-copilot-chat --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-26129?

365 copilot chat: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-26129 being exploited?

CVE-2026-26129 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-26129 affect?

CVE-2026-26129 affects 365 copilot chat. Severity is high (CVSS 7.5). Improper neutralization of special elements used in a command ('command injection') in M365 Copilot allows an unauthorized attacker to disclose information over a network.

How urgent is CVE-2026-26129?

Priority 53/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

Related CVEs

CVE-2026-26164 HIGH 7.5 MITIGATE Improper neutralization of special elements used in a command ('command injection') in M365 Copilot allows an

References

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