Security readout for executives and security teams
Plain-English summary
CVE-2026-21877 is a critical n8n vulnerability where an authenticated user could cause code to run on the n8n service. Successful exploitation could fully compromise affected self-hosted or n8n Cloud environments. The vendor states the issue is fixed in version 1.121.3.
Executive priority
Prioritize this immediately for any business-critical n8n use. The impact is full service compromise, and the required attacker privilege is low. Upgrade or confirm cloud remediation, then reduce access and disable unnecessary Git-node capability.
Technical view
The issue is described as remote code execution via arbitrary file write in n8n. It is network-accessible, low-complexity, requires low privileges, and no user interaction. CVSS is 10.0 with scope changed and high confidentiality, integrity, and availability impact. CWEs include unrestricted upload of dangerous file type and code injection.
Likely exposure
Any n8n deployment below 1.121.3 should be treated as exposed, including self-hosted and n8n Cloud instances per the advisory. Risk is higher where untrusted or broadly provisioned authenticated users can access n8n, especially if the Git node is enabled.
Exploitation context
The source bundle does not state active exploitation, and KEV status is false. Exploitation requires authentication but only low privileges, making insider misuse, compromised accounts, or over-permissioned users meaningful exposure paths.
Researcher notes
There is a version inconsistency in the provided data: the description says 0.121.2 and below, while affected versions list <1.121.3 and the fix is 1.121.3. Treat <1.121.3 as affected unless vendor guidance clarifies otherwise.
Mitigation direction
- Upgrade n8n to version 1.121.3 or later.
- Disable the Git node where it is not required.
- Limit n8n access for untrusted users.
- Review vendor advisory for updated cloud and self-hosted guidance.
Validation and detection
- Inventory all self-hosted and cloud n8n instances.
- Confirm each instance is running n8n 1.121.3 or later.
- Check whether the Git node is enabled.
- Review n8n user access for untrusted or unnecessary accounts.
- Monitor vendor advisory and CVE record for updates.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-434: File access and web shell behavior lookup
File traversal and upload weaknesses can lead teams to review file, web shell, execution, and collection telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-94: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupFile access behavior lookup
The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-21877 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 10 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H3.16Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
10CriticalVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/n8n-io/n8n/security/advisories/GHSA-v364-rw7m-3263CVE reference · x_refsource_CONFIRM
- https://github.com/n8n-io/n8n/commit/f4b009d00d1f4ba9359b8e8f1c071e3d910a55f6CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Unrestricted Upload of File with Dangerous Type
Unrestricted Upload of File with Dangerous Type represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Improper Control of Generation of Code ('Code Injection')
Improper Control of Generation of Code ('Code Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.