# CVE-2026-33337: Firebird has a buffer overflow when parsing corrupted slice packets

> An unauthenticated attacker can cause a buffer overflow in Firebird database by sending a crafted slice packet, leading to crashes or potential code execution.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Apr 2026
- **Updated:** 17 Apr 2026
- **Also known as:** DEBIAN-CVE-2026-33337, ECHO-0388-1371-3776, GHSA-89mq-229g-x47p, UBUNTU-CVE-2026-33337

## What is CVE-2026-33337?

CVE-2026-33337 is a high-severity memory corruption vulnerability in FirebirdSQL firebird, published on 17 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Firebird is an open-source relational database management system. In versions prior to 5.0.4, 4.0.7 and 3.0.14, when deserializing a slice packet, the xdr_datum() function does not validate that a cstring length conforms to the slice descriptor bounds, allowing a cstring longer than the allocated buffer to overflow it. An unauthenticated attacker can exploit this by sending a crafted packet to the server, potentially causing a crash or other security impact. This issue has been fixed in versions 5.0.4, 4.0.7 and 3.0.14.

Weakness: CWE-502 (Deserialization of Untrusted Data), CWE-120 (Buffer Copy without Checking Size of Input)

## Which versions are affected by CVE-2026-33337?

It affects 1 product.


Products: Firebirdsql Firebird.

## How do I fix CVE-2026-33337?

Upgrade to a fixed version.

## Is CVE-2026-33337 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33337 exists.

## Other vulnerabilities in FirebirdSQL firebird

- [CVE-2026-40342](https://insights.sbomify.com/CVE-2026-40342/): Firebird: Path Traversal + Arbitrary File Write Leads to Remote Code Execution (critical 10.0)
- [CVE-2008-0467](https://insights.sbomify.com/CVE-2008-0467/): Memory corruption in n/a (critical 10.0)
- [CVE-2007-4992](https://insights.sbomify.com/CVE-2007-4992/): Memory corruption in n/a (critical 10.0)
- [CVE-2007-5245](https://insights.sbomify.com/CVE-2007-5245/): Memory corruption in n/a (critical 10.0)
- [CVE-2007-5246](https://insights.sbomify.com/CVE-2007-5246/): Memory corruption in n/a (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33337 and fix it if it is affected.

What it is: CVE-2026-33337 is a high-severity memory corruption vulnerability in FirebirdSQL firebird, published on 17 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33337 exists.

Affected product: FirebirdSQL firebird. 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-2026-33337/ (Markdown: https://insights.sbomify.com/CVE-2026-33337/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33337
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33337
- OSV: https://osv.dev/vulnerability/CVE-2026-33337

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33337/
Summaries are generated and may contain mistakes; the official description above is the record.