CVE-2026-123380
A NVD · · CVE-2026-123380
Admiralty grading (A–F · 1–6)
Source reliability
- A Completely reliable
- B Usually reliable
- C Fairly reliable
- D Not usually reliable
- E Unreliable
- F Cannot be judged
Information credibility
- 1 Confirmed
- 2 Probably true
- 3 Possibly true
- 4 Doubtful
- 5 Improbable
- 6 Cannot be judged
NATO Admiralty (AJP-2.1) grades confidence, independent of the risk score. Cross-source corroboration isn't tracked for non-CVE news, so single-source items are capped at a lower credibility number; a low number does not imply low quality.
Key metrics
- CVSS
- 8.8
- EPSS
- 0%
Key insight
The NVD alert confirms a critical remote code execution vulnerability in Outlook but provides no indication of active exploitation or attacker TTPs.
Description
CVE-2026-123380 is a heap-based buffer overflow vulnerability in Microsoft Office Outlook. An unauthenticated attacker can execute code over the network through it. The alert comes from NVD and contains no information about public exploitation, proof-of-concept, or CISA KEV inclusion. Affected systems are Outlook installations; details on attack vectors and TTPs are not provided.
Risk score
- cvss base
- 88.00
- kev bonus
- 0.00
- epss bonus
- 0.00
- poc bonus
- 0.00
- raw before weight
- 88.00
- industry weight
- 1.21
- freshness factor
- 1.00
- exploitability factor
- 1.00
- days old
- 0.00
- vendor mismatch penalty
- 0.00
Path: operational
MITRE ATT&CK mapping
1 TTPProcedure details
| Technique | Tactic | Procedure | Conf. | Source |
|---|---|---|---|---|
| T1203 Exploitation for Client Execution | Execution | A heap-based buffer overflow in Microsoft Office Outlook is exploited by an unauthorized attacker to execute arbitrary code on the victim's system, likely through a specially crafted email or other network-delivered content. | high | llm |