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CVE-2026-61618

SNARK Verifier: noncanonical accumulator limb decoding

6.9 Medium

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
Low
Availability
None

Exploit likelihood

0.37%Unchanged since Oct 31, 2026
90%50%10%1%

What each source reports

CVE List Score used 6.9

SNARK Verifier: noncanonical accumulator limb decoding

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.

Record
CVE-2026-61618
CVSS 4.0
6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-20
Updated
2026-11-05
EUVDEUVD-2026-114397 6.9

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.

Record
EUVD-2026-114397
CVSS 4.0
6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Updated
2026-11-05
NVD 6.9

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.

Record
CVE-2026-61618
CVSS 4.0
6.9 MediumCVSS: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
Weakness
CWE-20
Updated
2026-11-05
OSV 6.9

SNARK Verifier: noncanonical accumulator limb decoding

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.

Record
CVE-2026-61618
CVSS 4.0
6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-20
Updated
2026-11-05

Affected products

History

History
RecordedChangedSources
factsNVD, OSV
first indexedCVE List, EUVD, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-61618 is a medium vulnerability (CVSS 6.9) in Axiom-crypto Snark-verifier, published October 30, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.37%, the 31st percentile. No source names a fixed version.

References

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