CVE-2026-62337
SNARK Verifier: Halo 2 aggregation mishandles point-at-infinity proof elements
What happened?
SNARK Verifier is a generic (S)NARK verifier. Prior to 0.2.5, the Halo 2 aggregation circuit can mishandle proof points encoded as the point at infinity. `EcPointLoader::multi_scalar_multiplication` places a `Value::Assigned(_)` base paired with `Value::Constant(ONE)` into its unscaled variable-base list and passes it directly to `sum_with_const`. The default shim delegates to halo2-lib `EccChip::sum`, whose incomplete affine addition assumes nonidentity input points. A prover-controlled proof point encoded as `(0, 0)` can therefore enter the final aggregation sum through the scalar-one shortcut and affect the MSM or accumulator computation. Practical exploitability depends on the surrounding aggregation and final-decider checks; the advisory does not establish universal acceptance of invalid proofs. This issue is fixed in version 0.2.5.
Affected software and versions
| Software | Version information | Fixed version |
|---|---|---|
| snark-verifieraxiom-crypto | affected: < 0.2.5 | See vendor advisory |
Version information comes from the source record and can include unaffected products and exceptions. Distribution packages may contain backported fixes: an older upstream version alone does not prove a server is affected.
Is it being exploited?
This CVE was not listed in the CISA catalogue at our last retrieval. This does not establish that exploitation is absent.
How to respond
- Confirm the product, installed package version, and any configuration requirements in the vendor advisory.
- Follow the vendor’s remediation or workaround guidance in the references below. Structured fixed-version data is unavailable here; the publisher’s description may include a fix or workaround.
- Restart affected services if required, then verify the running version. Known exploitation may warrant investigation as well as patching.
Sources and remediation references
- https://www.cve.org/CVERecord?id=CVE-2026-62337
- https://github.com/axiom-crypto/snark-verifier/security/advisories/GHSA-x26x-7f4v-cqx7
- https://github.com/axiom-crypto/halo2-lib/commit/f53be0939e2accf0dd7672b1a4abe80af73dadf3
- https://github.com/axiom-crypto/snark-verifier/commit/bbfcc721d714bea0d44a27c8fc6c4736e73ca853
- https://github.com/axiom-crypto/snark-verifier/releases/tag/v0.2.5