CVE-2026-40323 SP1 V6 Recursion Circuit Row-Count Binding Gap
A malicious prover can bypass verification in the SP1 ZK virtual machine by constructing invalid recursive proofs, compromising proof integrity.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-40323?
CVE-2026-40323 is a high-severity vulnerability in succinctlabs sp1, published on 17 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
SP1 is a zero‑knowledge virtual machine that proves the correct execution of programs compiled for the RISC-V architecture. In versions 6.0.0 through 6.0.2, a soundness vulnerability in the SP1 V6 recursive shard verifier allows a malicious prover to construct a recursive proof from a shard proof that the native verifier would reject. Version 6.1.0 fixes the issue.
Which versions are affected by CVE-2026-40323?
6 open source packages ship an affected version, including sp1_prover, sp1_recursion_circuit and sp1_sdk. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
sp1_prover crates.io | From 6.0.0 | 6.1.0 |
sp1_prover crates.io | From 6.0.0 | 6.1.0 |
sp1_recursion_circuit crates.io | From 6.0.0 | 6.1.0 |
sp1_recursion_circuit crates.io | From 6.0.0 | 6.1.0 |
sp1_sdk crates.io | From 6.0.0 | 6.1.0 |
sp1_sdk crates.io | From 6.0.0 | 6.1.0 |
Products include Succinct Sp1.
How do I fix CVE-2026-40323?
Upgrade sp1_prover to 6.1.0 or later.
Is CVE-2026-40323 being exploited?
There is no known exploitation of CVE-2026-40323 in the wild and no public exploit code.
Sources
Also known as GHSA-63x8-x938-vx33.