# CVE-2026-71558: Apache Fory: Heap type confusion in C++ polymorphic smart-pointer deserialization

> A heap type confusion in Apache Fory C++ allows attackers to execute arbitrary code or cause denial of service via crafted deserialization payloads.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 7 Aug 2026
- **Updated:** 7 Aug 2026
- **Also known as:** GHSA-rwv5-p9fv-c8fp

## What is CVE-2026-71558?

CVE-2026-71558 is a critical unsafe deserialization vulnerability in Apache Fory, published on 7 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Heap type confusion vulnerability in Apache Fory C++ deserialization.

This issue affects Apache Fory C++ versions from 0.14.0 before 1.5.0. A crafted input payload can bypass type compatibility checks during polymorphic smart-pointer deserialization, causing an object of an incompatible type to be treated as the declared base type. This may result in undefined behavior and potentially lead to denial of service or arbitrary code execution.

Users are recommended to upgrade to Apache Fory 1.5.0, which fixes this issue. Applications not using Apache Fory C++ polymorphic smart-pointer deserialization are not affected.

Weakness: CWE-843 (Access of Resource Using Incompatible Type), CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2026-71558?

It affects 1 product.


Products: Apache Fory.

## How do I fix CVE-2026-71558?

No fix has been published for CVE-2026-71558 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-71558 being exploited?

There is no known exploitation of CVE-2026-71558 in the wild and no public exploit code.

## Other vulnerabilities in Apache Fory

- [CVE-2026-64606](https://insights.sbomify.com/CVE-2026-64606/): Apache Fory, Apache Fory: Class-registration bypass through an auto-admitted SerializedLambda capturing interface (critical 9.8)
- [CVE-2026-64608](https://insights.sbomify.com/CVE-2026-64608/): Apache Fory: Heap type confusion and out-of-bounds read/write in C++ compatible-mode field-skip paths (critical 9.8)
- [CVE-2026-48207](https://insights.sbomify.com/CVE-2026-48207/): Apache Fory: PyFory ReduceSerializer Incomplete Policy Enforcement (critical 9.8)
- [CVE-2025-61622](https://insights.sbomify.com/CVE-2025-61622/): Apache Fory, Apache Fory: Python RCE via unguarded pickle fallback serializer in pyfory (critical 9.8)
- [CVE-2026-71560](https://insights.sbomify.com/CVE-2026-71560/): Apache Fory: Out-of-bounds heap read in C++ struct deserializer tagged-int fast-path (critical 9.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-71558 and fix it if it is affected.

What it is: CVE-2026-71558 is a critical unsafe deserialization vulnerability in Apache Fory, published on 7 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-71558 in the wild and no public exploit code.

Affected product: Apache Fory. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-71558/ (Markdown: https://insights.sbomify.com/CVE-2026-71558/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-71558
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-71558
- OSV: https://osv.dev/vulnerability/CVE-2026-71558

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-71558/
Summaries are generated and may contain mistakes; the official description above is the record.