# CVE-2026-21887: OpenCTI has a Semi-Blind SSRF via Unvalidated External URL in Data Ingestion Feature

> Attackers can exploit unvalidated URLs in data ingestion to perform semi-blind SSRF attacks against internal services.

- **Severity:** High 7.7 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 12 Mar 2026
- **Updated:** 12 Mar 2026
- **Also known as:** GHSA-ffm6-vvph-g5f5, PYSEC-2026-118

## What is CVE-2026-21887?

CVE-2026-21887 is a high-severity server-side request forgery vulnerability in OpenCTI-Platform opencti, published on 12 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

OpenCTI is an open source platform for managing cyber threat intelligence knowledge and observables. Prior to 6.8.16, the OpenCTI platform’s data ingestion feature accepts user-supplied URLs without validation and uses the Axios HTTP client with its default configuration (allowAbsoluteUrls: true). This allows attackers to craft requests to arbitrary endpoints, including internal services, because Axios will accept and process absolute URLs. This results in a semi-blind SSRF, as responses may not be fully visible but can still impact internal systems. This vulnerability is fixed in 6.8.16.

Weakness: CWE-918 (Server-Side Request Forgery)

## Which versions are affected by CVE-2026-21887?

3 open source packages ship an affected version, including pycti. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `pycti` | PyPI | All versions | 6.8.16 |
| `pycti` | PyPI | All versions | 6.8.16 |
| `pycti` | PyPI | All versions | 6.8.16 |

Products: Citeum Opencti.

## How do I fix CVE-2026-21887?

Upgrade pycti to 6.8.16 or later.

## Is CVE-2026-21887 being exploited?

There is no known exploitation of CVE-2026-21887 in the wild and no public exploit code.

## Other vulnerabilities in OpenCTI-Platform opencti

- [CVE-2026-27960](https://insights.sbomify.com/CVE-2026-27960/): OpenCTI privilege escalation and unauthenticated access via default admin account (critical 9.8)
- [CVE-2026-39980](https://insights.sbomify.com/CVE-2026-39980/): OpenCTI affected by RCE via notifier template (critical 9.1)
- [CVE-2025-24977](https://insights.sbomify.com/CVE-2025-24977/): OpenCTI has remote code execution and sensitive secrets exposed through web hook (critical 9.1)
- [CVE-2024-26139](https://insights.sbomify.com/CVE-2024-26139/): OpenCTI Authenticated Privilege Escalation (high 8.3)
- [CVE-2024-45404](https://insights.sbomify.com/CVE-2024-45404/): OpenCTI's lack of Rate Limit lead to OTP brute forcing (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-21887 and fix it if it is affected.

What it is: CVE-2026-21887 is a high-severity server-side request forgery vulnerability in OpenCTI-Platform opencti, published on 12 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-21887 in the wild and no public exploit code.

Affected packages and fixed versions:
- pycti (PyPI): affected all versions; fixed in 6.8.16
- pycti (PyPI): affected all versions; fixed in 6.8.16
- pycti (PyPI): affected all versions; fixed in 6.8.16

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-2026-21887/ (Markdown: https://insights.sbomify.com/CVE-2026-21887/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-21887
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-21887
- OSV: https://osv.dev/vulnerability/CVE-2026-21887

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-21887/
Summaries are generated and may contain mistakes; the official description above is the record.