# CVE-2026-61618: SNARK Verifier: noncanonical accumulator limb decoding

Status: published. Published: 2026-10-30. Updated: 2026-11-05.

SNARK Verifier is a generic (S)NARK verifier. Prior to 0.2.5, KZG accumulator public-instance limbs are decoded without consistently enforcing canonical limb bounds before elliptic-curve coordinate reconstruction. `PlonkProof::read` selects scalars using `accumulator_indices` and passes them to `AccumulatorEncoding::from_repr`. For the EVM loader, `LimbsEncoding::from_repr` forwards them to `EvmLoader::ec_point_from_limbs` in `snark-verifier/src/loader/evm/loader.rs`, where `shl` and `add` reconstruct coordinates before `validate_ec_point` checks the resulting affine point rather than the original limb bounds. The related native path in `snark-verifier/src/pcs/kzg/accumulator.rs` can reach assertion- or unwrap-based decoding and panic instead of returning a verification error. This allows noncanonical encodings at the verifier boundary and can crash the native verifier. Standard SDK aggregation circuits are expected to constrain accumulator limbs before this boundary, which limits practical exploitability. This issue is fixed in version 0.2.5.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- axiom-crypto / snark-verifier: < 0.2.5 (affected). Source: CNA: GitHub_M
-  / snark-verifier (snark-verifier): < 0.2.5 (affected, GitHub advisory range). Source: GitHub GHSA-265x-v3qf-ff6p

## Severity and prioritization

- CVSS 4.0: 6.9 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N; source: CNA: GitHub_M

- CVSS 4.0: 6.9 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/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; source: NVD: security-advisories@github.com

- CISA KEV: No listing in collected sources

- EPSS: 0.37% as of 2026-11-04; percentile 31.23%

- SSVC: exploitation none; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-20

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/axiom-crypto/snark-verifier/security/advisories/GHSA-265x-v3qf-ff6p (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/axiom-crypto/snark-verifier/commit/d6aaf66d4706f5317cf61d5dbe00c14e7fbdbb70 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/axiom-crypto/snark-verifier/releases/tag/v0.2.5 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/axiom-crypto/snark-verifier/commit/d6aaf66d4706f5317cf61d5dbe00c14e7fbdbb70 (security-advisories@github.com)

- https://github.com/axiom-crypto/snark-verifier/releases/tag/v0.2.5 (security-advisories@github.com)

- https://github.com/axiom-crypto/snark-verifier/security/advisories/GHSA-265x-v3qf-ff6p (security-advisories@github.com)

- https://github.com/axiom-crypto/snark-verifier/security/advisories/GHSA-265x-v3qf-ff6p (GitHub Security Advisories; advisory)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-61618; retrieved 2026-11-05; source updated 2026-11-05

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-61618; retrieved 2026-11-03; source updated 2026-11-02

- GitHub Security Advisories: https://github.com/axiom-crypto/snark-verifier/security/advisories/GHSA-265x-v3qf-ff6p; retrieved 2026-11-03; source updated 2026-07-10

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-61618; retrieved 2026-11-05; source updated Not reported

Revision: 4bb3c6209367e0a62b8cdbaeb3bc2d6c3d77ff3a55ccac8e818242fd4e81fb40

Canonical: https://y2.dev/cve/CVE-2026-61618

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