# CVE-2026-55764: Klever-Go: SFT add-quantity `int64` overflow bypasses a finite per-nonce MaxSupply

> A mint-role holder can exploit an integer overflow to bypass supply limits and mint excessive tokens, corrupting the blockchain state.

- **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:** 28 Aug 2026
- **Updated:** 31 Aug 2026
- **Also known as:** GHSA-mrpp-v6pg-p54x, GO-2026-6330

## What is CVE-2026-55764?

CVE-2026-55764 is a high-severity vulnerability in klever-io klever-go, published on 28 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. Prior to 1.7.19, Klever-Go allows a mint-role holder to bypass a finite per-nonce MaxSupply on the semi-fungible token add-quantity path. In core/kapp/systemAccount/systemAcount.go, SFTAddCirculation performed meta.Circulation += amount before evaluating whether Circulation exceeded MaxSupply, without checking for signed int64 overflow. A large positive raw Amount supplied through processSemiFungibleAddQuantity in core/kapp/kda/mint.go can wrap Circulation negative, causing the signed maximum-supply comparison to pass and crediting approximately MaxInt64 units while corrupting the on-chain counter. The fungible path is not affected because its MintedValue <= 0 guard detects the overflow. The correction uses the consensus activation flag FixMarketBuyOverflow. This issue is fixed in version 1.7.19.

Weakness: CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2026-55764?

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 | 1.7.19 |
| `github.com/klever-io/klever-go` | Go | All versions | 1.7.19 |
| `github.com/klever-io/klever-go` | Go | All versions | 1.7.19 |

## How do I fix CVE-2026-55764?

Upgrade github.com/klever-io/klever-go to 1.7.19 or later.

## Is CVE-2026-55764 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55764 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-55764 and fix it if it is affected.

What it is: CVE-2026-55764 is a high-severity vulnerability in klever-io klever-go, published on 28 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-2026-55764 exists.

Affected packages and fixed versions:
- github.com/klever-io/klever-go (Go): affected all versions; fixed in 1.7.19
- github.com/klever-io/klever-go (Go): affected all versions; fixed in 1.7.19
- github.com/klever-io/klever-go (Go): affected all versions; fixed in 1.7.19

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-2026-55764/ (Markdown: https://insights.sbomify.com/CVE-2026-55764/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-55764
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-55764
- OSV: https://osv.dev/vulnerability/CVE-2026-55764

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-55764/
Summaries are generated and may contain mistakes; the official description above is the record.