No exploitation reported

CVE-2021-3277

No exploitation reported by the sources we read.

Published2021-06-07
WeaknessCWE-434

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Nagios XI 5.7.5 and earlier allows authenticated admins to upload arbitrary files due to improper validation of the rename functionality in custom-includes component, which leads to remote code execution by uploading php files.

Timeline

dates in UTC

2021-06-0722:15CVE publishedNVD
2026-10-2319:23EPSS crossed 10 %FIRST EPSS

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-3277?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-3277?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Nagios nagios xi

Branch	Affected	Fixed in	Source
5.7	≤ 5.7.5	no fix published	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

No fix published by the sources we read yet. NVD record

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.17.2read 2026-10-23
NVDCVSS 2.06.5read 2026-10-23
NVDweakness (CWE)CWE-434read 2026-10-23
FIRST EPSSEPSS score54.6 %read 2026-10-23

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Published: 2021-06-07
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-3277?

Is CVE-2021-3277 actively exploited?

Active exploitation of CVE-2021-3277 has not been confirmed. Its EPSS score was 54.6% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-3277?

CVE-2021-3277 has a CVSS v3 base score of 7.2 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H.

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