SP1 V6 Recursion Circuit Row-Count Binding Gap

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

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.

Source published

17 Apr 2026 22:58:42 UTC

Source modified

20 Apr 2026 16:16:41 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 4.0 · 8.9 CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N

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.

Source published

Apr 17, 2026, 10:58:42 PM (timezone not stated)

Source modified

Apr 20, 2026, 4:16:41 PM (timezone not stated)

Observed here

28 Oct 2026 05:02:09 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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EUVD CVSS 4.0 · 8.9 CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N

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.

Source published

18 Apr 2026 00:16:36 UTC

Source modified

26 Oct 2026 21:10:00 UTC

Observed here

27 Oct 2026 10:09:56 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 8.9 CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS 3.1 · [email protected] · Primary · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

## Summary 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. - **Affected versions:** `>= 6.0.0, <= 6.0.2` - **Not affected:** SP1 V5 (all versions) - **Severity:** High ## Details ### Background The recursive shard verifier circuit verifies shard proofs inside a recursive proof. Each shard proof includes a jagged PCS opening, which binds trace-shape metadata into a modified commitment and uses that same shape to evaluate the committed polynomials. These two operations must agree on the committed table heights. ### The Bug In the V6 recursion circuit's jagged verifier, the two checks above are served by separate witnesses: a vector of row counts hashed into the modified commitment (commitment side), and a separate witness of prefix sums derived from row and column counts that drives the jagged polynomial evaluator (evaluation side). The prefix sums are observed within the shard verifier. The consistency check between these two witnesses was missing in the recursion sub-circuit describing the jagged PCS verifier. A malicious prover can therefore supply one trace shape for commitment binding and a different shape for polynomial evaluation. ### Potential Impact The vulnerability applies to both main trace and preprocessed trace metadata. Because preprocessed traces encode circuit structure (selectors, fixed columns, permutation layout), the potential impact extends beyond data forgery to misrepresentation of the circuit itself. While a demonstration of a full exploit proving arbitrary statements has not been created — since modifying one table's layout incidentally constrains changes to related tables — this barrier is not by design and should not be relied upon. This is considered a soundness violation that is unacceptable regardless of current exploitability. ### Why the Native Verifier Is Not Affected The native shard verifier uses a single jagged PCS verifier object where row counts and evaluation layout are derived from the same data, so the split-witness divergence cannot occur. The recursion circuit's shard-level checks (prefix-sum and total-area assertions) only constrain the evaluation-side parameters, not the commitment-side row counts, so they do not catch the gap. ## Mitigation The fix adds a post-evaluation consistency constraint in the recursive jagged verifier. After the jagged evaluation returns the prefix-sum values derived from the evaluation layout, the circuit reconstructs expected prefix sums from the commitment-side row counts (repeating each row count by its corresponding column count and accumulating). It then asserts element-wise equality between the reconstructed and returned prefix sums, and verifies that the final accumulated area matches the total area from the evaluation parameters. This forces both witnesses to describe the same trace geometry. Any divergence is now a constraint failure. ## Credit This vulnerability was identified through the SP1 bug bounty program on Code4rena.

Source published

14 Apr 2026 00:05:19 UTC

Source modified

5 May 2026 16:02:07 UTC

Observed here

24 Oct 2026 13:19:54 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N

Publisher rating · HIGH