Answer in brief
CVE-2026-63634 records a Medium severity (CVSS 6.9) vulnerability in pympp: Gas Draining with padding. The current sources do not mark it as known exploited. The current feed maps tempoxyz/pympp (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 6.9. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps tempoxyz/pympp (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| tempoxyz/pymppgeneric | <0.9.1 | 0.9.1 |
Published upstream
Nov 9, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Nov 9, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Nov 9, 2026
pympp is a Python SDK for the Machine Payments Protocol. Prior to version 0.9.1, when the server acts as the fee_payer, pympp validates calldata using eth_abi decoding, which is lenient about trailing bytes. The FeePayerPolicy caps gas_limit (≤ 2 M) and max_fee_per_gas (≤ 100 Gwei) but does not check calldata length. Tempo uses legacy calldata gas pricing: 16 gas per non-zero byte. Appending N bytes of 0x01 padding inflates actual gas used by N × 16 while keeping gas_limit and max_fee_per_gas within policy caps. The server cosigns and broadcasts the padded transaction, draining its fee-payer wallet. This issue has been patched in version 0.9.1.
Quoted source text, attributed separately from HOL analysis.