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TI-2026-83349 Aliases CVE-2026-61618

Noncanonical accumulator limb decoding in SNARK Verifier

Priority LOW 37CWE-20Published · Updated

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

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00371 31st percentileScored 2026-11-07
Fix Fixed snark-verifier (axiom-crypto): 0.2.5

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

VendorProductAffected versionsFixed inStatusSource
axiom-cryptosnark-verifierbefore 0.2.50.2.5Patch availableCNA
  • 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

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-30 Threatist record created from CVE-2026-61618
  2. 2026-11-01 Priority changed: MEDIUM → LOW
  3. 2026-11-05 CISA SSVC decision points changed
  4. 2026-11-06 Affected versions changed · Red Hat
  5. 2026-11-06 CVSS score added · Red Hat

References

  • TI-2026-83377 Point-at-infinity handling flaw in SNARK Verifier Halo 2 aggregation CVSS 4.0MEDIUM 6.9

Sources