Home/CVE/n8n before 2.25.7 and 2.26.x before 2.26.2 contains an abstract syntax tree (AST) security validator bypass in the Pytho
CVE
CVE-2026-56777
n8n before 2.25.7 and 2.26.x before 2.26.2 contains an abstract syntax tree (AST) security validator bypass in the Pytho
n8n before 2.25.7 and 2.26.x before 2.26.2 contains an abstract syntax tree (AST) security validator bypass in the Python Code node. An authenticated user with permission to create or modify workflows containing a Python Code node can bypass the validator and access the task executor module namespace. The issue only affects self-hosted instances where the Python Task Runner is enabled.
where N8N_BLOCK_RUNNER_ENV_ACCESS is configured to allow it, this can disclose environment variables accessible to the task runner process.
MEDIUM · CVSS 5
Monitor
- No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
No Sigma yet — build one →
YARA rules0
Look this up elsewhere - one-click external pivots
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How to read a CVE - triage first, then detect and patch
This page is every public fact about CVE-2026-56777, cross-linked. Its job is to answer one question fast - does this need my attention now? - and then hand you the two things you do about it. Here is how an analyst reads it.
Triage: should I act now? Four signals, and they are not interchangeable:
CVSSseverity - how bad it is IF exploited, 0-10. A high CVSS alone is not urgency; a flaw can be a perfect 10 and never actually be attacked.
EPSSprobability - a model’s estimate of the chance it is exploited in the next 30 days, 0-1. This is the “will it actually happen” signal.
CISA KEVconfirmed - it is being exploited in the wild right now. The strongest signal on the page; KEV beats any score.
Weaponisedavailability - public exploits / PoCs, and especially Metasploit modules rated Excellent / Great. Reliable, packaged exploit code means low-skill attackers can use it today.
How they combine: KEV, or a dependable Metasploit module, means patch now regardless of CVSS. High CVSS + low EPSS + no exploit is real but not an emergency - schedule it. Low CVSS but KEV-listed still gets patched now. The verdict above already weighed these for you; this is how it got there.
Then what - two workflows:
Detectwhen you cannot patch today, follow this CVE to the ATT&CK techniques it enables, then Build a SIEM detection (the green button) - author a rule, test it in Atomic, deploy it. That buys visibility while the patch waits.
PatchAffected products / packages tell you if you are exposed; Fixed versions by distribution and Vendor advisories give the exact version that closes it.
Reading order for the panels below: verdict + badges, then Public exploits / Metasploit (is it weaponised), then ATT&CK techniques + Sigma / IDS rules (can I detect it), then Affected products / packages + Fixed versions (am I exposed, what patches it), then Threat actors / IOCs (who uses it), then Scoring & timeline / references (the evidence).
EPSS exploitation probability
n/a
No EPSS score in our data for this CVE. EPSS is published daily for scored CVEs - a very new, reserved, or rejected CVE may not have one yet.
CVSS metric silhouette
shape grows toward worst-case
SSVC triage
No SSVC vulnrichment for this CVE. CISA's Vulnrichment program scores newer CVEs (~2024 onwards) plus selected older critical ones. Use the EPSS probability + KEV status to triage instead.
CVSS vector breakdown
Exploitability - how they get in
Attack Vector
Network
Adjacent
Local
Physical
Attack Complexity
Low
High
Privileges Required
None
Low
High
User Interaction
None
Required
Scope
Unchanged
Changed
Impact - what breaks
Confidentiality
None
Low
High
Integrity
None
Low
High
Availability
None
Low
High
VECTOR
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N◆
ATT&CK techniques
1Techniques this CVE enables. Pills with a solid outline are high confidence - named directly in ATT&CK or Nuclei, or human-curated by CTID; the rest are inferred from the weakness type using MITRE's CVE Mapping Methodology and the CWE → CAPEC chain. Broad, generic-weakness guesses are filtered out. A small N× marks a technique that N independent sources agree on.
▤ Build a SIEM detection for these techniques▤
CAPEC attack patterns
9Attack patterns this CVE enables - the bridge from weakness to ATT&CK technique.
CAPEC-CAPEC-120 · Double Encoding CAPEC-CAPEC-15 · Command Delimiters CAPEC-CAPEC-182 · Flash Injection CAPEC-CAPEC-3 · Using Leading 'Ghost' Character Sequences to Bypass Input Filters CAPEC-CAPEC-43 · Exploiting Multiple Input Interpretation Layers CAPEC-CAPEC-6 · Argument Injection CAPEC-CAPEC-71 · Using Unicode Encoding to Bypass Validation Logic CAPEC-CAPEC-73 · User-Controlled Filename CAPEC-CAPEC-85 · AJAX Footprinting
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Weakness Classification
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Related CVEs
4CVEs linked to this one by a shared weakness (CWE) or affected product - joins on data already in the engine, with the reason shown per row.
CVE-2015-5946
Incomplete blacklist vulnerability in SuiteCRM 7.2.2 allows remote authenticated...
same CWE-184
HIGH
CVE-2016-6189
Incomplete blacklist in SOGo before 2.3.12 and 3.x before 3.1.1 allows remote au...
same CWE-184
MEDIUM
CVE-2016-7076
sudo before version 1.8.18p1 is vulnerable to a bypass in the sudo noexec restri...
same CWE-184
MEDIUM
CVE-2017-7540
rubygem-safemode, as used in Foreman, versions 1.3.2 and earlier are vulnerable ...
same CWE-184
CRITICAL
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References & Sources
2Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.