Vulnerability · Published Oct 30, 2026 · Assigned by GitHub_M
CVE-2026-62337SNARK Verifier: Halo 2 aggregation mishandles point-at-infinity proof elements
Medium 6.9
In plain English
A medium-severity improper input validation in snark-verifier from axiom-crypto. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 23% of all known vulnerabilities).
Official description
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 products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| axiom-crypto | snark-verifier | < 0.2.5 |
Weakness: CWE-20 · Vector: 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
References
- https://github.com/axiom-crypto/snark-verifier/security/advisories/GHSA-x26x-7f4v-cqx7 x_refsource_CONFIRM
- https://github.com/axiom-crypto/halo2-lib/commit/f53be0939e2accf0dd7672b1a4abe80af73dadf3 x_refsource_MISC
- https://github.com/axiom-crypto/snark-verifier/commit/bbfcc721d714bea0d44a27c8fc6c4736e73ca853 x_refsource_MISC
- https://github.com/axiom-crypto/snark-verifier/releases/tag/v0.2.5 x_refsource_MISC