# CVE-2026-40943: Oxia: Server crash via race condition in session heartbeat handling

> A race condition in Oxia's session heartbeat handling allows attackers to crash the server via a panic or deadlock.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 21 Apr 2026
- **Updated:** 22 Apr 2026
- **Also known as:** GHSA-5gqc-qhrj-9xw8, GO-2026-5145

## What is CVE-2026-40943?

CVE-2026-40943 is a high-severity vulnerability in oxia-db oxia, published on 21 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Oxia is a metadata store and coordination system. Prior to 0.16.2, a race condition between session heartbeat processing and session closure can cause the server to panic with send on closed channel. The heartbeat() method uses a blocking channel send while holding a mutex, and under specific timing with concurrent close() calls, this can lead to either a deadlock (channel buffer full) or a panic (send on closed channel after TOCTOU gap in KeepAlive). This vulnerability is fixed in 0.16.2.

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2026-40943?

3 open source packages ship an affected version, including github.com/oxia-db/oxia.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/oxia-db/oxia` | Go | All versions | 0.16.2 |
| `github.com/oxia-db/oxia` | Go | All versions | 0.16.2 |
| `github.com/oxia-db/oxia` | Go | All versions | 0.16.2 |

## How do I fix CVE-2026-40943?

Upgrade github.com/oxia-db/oxia to 0.16.2 or later.

## Is CVE-2026-40943 being exploited?

There is no known exploitation of CVE-2026-40943 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40943 and fix it if it is affected.

What it is: CVE-2026-40943 is a high-severity vulnerability in oxia-db oxia, published on 21 Apr 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-2026-40943 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/oxia-db/oxia (Go): affected all versions; fixed in 0.16.2
- github.com/oxia-db/oxia (Go): affected all versions; fixed in 0.16.2
- github.com/oxia-db/oxia (Go): affected all versions; fixed in 0.16.2

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-2026-40943/ (Markdown: https://insights.sbomify.com/CVE-2026-40943/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40943
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40943
- OSV: https://osv.dev/vulnerability/CVE-2026-40943

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-40943/
Summaries are generated and may contain mistakes; the official description above is the record.