# CVE-2026-56837: PraisonAI LinearBot processes unsigned webhooks when LINEAR_WEBHOOK_SECRET is missing


- **Severity:** High 8.6 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 23 Oct 2026
- **Updated:** 23 Oct 2026
- **Also known as:** GHSA-fc26-m9pf-v56q, PYSEC-2026-3510

## What is CVE-2026-56837?

CVE-2026-56837 is a high-severity vulnerability in MervinPraison PraisonAI, published on 23 Oct 2026. 

### Official description

PraisonAI is a multi-agent teams system. From version 4.6.56 to before version 4.6.59, PraisonAI's LinearBot starts a public webhook listener on 0.0.0.0 and treats LINEAR_WEBHOOK_SECRET as optional. When the secret is absent, startup only logs a warning and _handle_webhook() skips Linear-Signature verification entirely. An unauthenticated network caller who can reach the webhook endpoint can submit a forged Linear-Event: AgentSession request. The forged request is parsed, scheduled for background processing, dispatched to _handle_agent_session(), and passed into BotSessionManager.chat(). The bot then attempts to post the agent response back to Linear under the configured bot token. The PoV is offline and deterministic. It does not contact Linear. It calls the webhook handler directly, monkey-patches the outbound Linear comment path, and proves both sides of the boundary. This issue has been patched in version 4.6.59.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature), CWE-306 (Missing Authentication for Critical Functionality), CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2026-56837?

3 open source packages ship an affected version, including praisonai.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `praisonai` | PyPI | From 4.6.56 | 4.6.59 |
| `praisonai` | PyPI | From 4.6.56 | 4.6.59 |
| `praisonai` | PyPI | From 4.6.56 | 4.6.59 |

## How do I fix CVE-2026-56837?

Upgrade praisonai to 4.6.59 or later.

## Is CVE-2026-56837 being exploited?

There is no known exploitation of CVE-2026-56837 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-56837 and fix it if it is affected.

What it is: CVE-2026-56837 is a high-severity vulnerability in MervinPraison PraisonAI, published on 23 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-56837 in the wild and no public exploit code.

Affected packages and fixed versions:
- praisonai (PyPI): affected from 4.6.56; fixed in 4.6.59
- praisonai (PyPI): affected from 4.6.56; fixed in 4.6.59
- praisonai (PyPI): affected from 4.6.56; fixed in 4.6.59

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-56837/ (Markdown: https://insights.sbomify.com/CVE-2026-56837/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-56837
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-56837
- OSV: https://osv.dev/vulnerability/CVE-2026-56837

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-56837/
Summaries are generated and may contain mistakes; the official description above is the record.