Noncanonical accumulator limb decoding in SNARK Verifier
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- None · Low · None
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA.
Summary
The axiom-crypto snark-verifier package is affected before 0.2.5. KZG accumulator limbs are decoded without consistently enforcing canonical bounds, which is improper input validation (CWE-20). A remote attacker without privileges can submit noncanonical encodings at the verifier boundary, and the native path can panic and crash the verifier. Standard SDK aggregation circuits are expected to constrain the limbs first, which limits practical exploitability.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| axiom-crypto | snark-verifier | before 0.2.5 | 0.2.5 | Patch available | CNA |
- snark-verifier Vendoraxiom-crypto Affected before 0.2.5 Fixed in 0.2.5 Patch available CNA
Remediation
Upgrade axiom-crypto snark-verifier to version 0.2.5, which fixes the issue.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA snark-verifier (axiom-crypto) Fixed in 0.2.5
Vendor assessments
Timeline
- 2026-10-30 Threatist record created from CVE-2026-61618
- 2026-11-01 Priority changed: MEDIUM → LOW
- 2026-11-05 CISA SSVC decision points changed
- 2026-11-06 Affected versions changed · Red Hat
- 2026-11-06 CVSS score added · Red Hat
References
More axiom-crypto vulnerabilities
- TI-2026-83377 Point-at-infinity handling flaw in SNARK Verifier Halo 2 aggregation CVSS 4.0MEDIUM 6.9
Sources
- CVE-2026-61618 · CVE Program
- CVE-2026-61618 · NVD
- FIRST EPSS
- CVE-2026-61618 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences