# CVE-2026-49343: Klever-Go KVM: Throttler slot leak in trie account-data sync causes epoch bootstrap / state sync DoS

> Attackers can exhaust throttler slots via sync errors, causing denial of service during node bootstrap or state synchronization in Klever-Go.

- **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/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:** 7 Aug 2026
- **Updated:** 13 Aug 2026
- **Also known as:** GHSA-fw38-pc54-jvx9, GO-2026-5379

## What is CVE-2026-49343?

CVE-2026-49343 is a medium-severity denial of service vulnerability in klever-io klever-go, published on 7 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Klever-Go is the Go implementation of the Klever blockchain protocol. In versions prior to 1.7.18, the account-data trie syncers are vulnerable to a resource-exhaustion flaw that leaks bounded throttler slots on error paths. In syncDataTrie() (in both userAccountsSyncer.go and kappAccountsSyncer.go), StartProcessing() reserves a slot from the NumGoRoutinesThrottler, but the corresponding EndProcessing() is only called on the success path and on the duplicate-root early return. As a result, any error from trie.NewTrie(), trie.NewTrieSyncer(), or trieSyncer.StartSyncing() (including the network-dependent timeout path) permanently consumes one slot for the lifetime of the throttler. An attacker who can repeatedly cause trie-node sync failures or timeouts during bootstrap can exhaust the bounded throttler, after which further account-data trie syncs stop making progress and SyncAccounts() returns a timeout. Because epoch bootstrap in syncUserAccountsState() and syncKappAccountsState() aborts on any such error, this causes bootstrap to fail, a core availability issue affecting fresh, restarting, or resyncing nodes and validators. This issue is fixed in version 1.7.18.

Weakness: CWE-772 (Missing Release of Resource after Effective Lifetime), CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-49343?

3 open source packages ship an affected version, including github.com/klever-io/klever-go.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/klever-io/klever-go` | Go | All versions | 1.7.18 |
| `github.com/klever-io/klever-go` | Go | All versions | 1.7.18 |
| `github.com/klever-io/klever-go` | Go | All versions | 1.7.18 |

## How do I fix CVE-2026-49343?

Upgrade github.com/klever-io/klever-go to 1.7.18 or later.

## Is CVE-2026-49343 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49343 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-49343 and fix it if it is affected.

What it is: CVE-2026-49343 is a medium-severity denial of service vulnerability in klever-io klever-go, published on 7 Aug 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-2026-49343 exists.

Affected packages and fixed versions:
- github.com/klever-io/klever-go (Go): affected all versions; fixed in 1.7.18
- github.com/klever-io/klever-go (Go): affected all versions; fixed in 1.7.18
- github.com/klever-io/klever-go (Go): affected all versions; fixed in 1.7.18

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-2026-49343/ (Markdown: https://insights.sbomify.com/CVE-2026-49343/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-49343
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-49343
- OSV: https://osv.dev/vulnerability/CVE-2026-49343

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-49343/
Summaries are generated and may contain mistakes; the official description above is the record.