kora-lib: Token-2022 Transfer Fee Not Deducted During Payment Verification

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

not scored

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary When a user pays transaction fees using a Token-2022 token with a TransferFeeConfig extension, Kora's verifytokenpayment() credits the full raw transfer amount as the payment value. However, the on-chain SPL Token-2022 program withholds a portion of that amount as a transfer fee, so the paymaster's destination account only receives amount - transferfee. This means the paymaster consistently credits more value than it actually receives, resulting in systematic financial loss. Severity High Affected Component - File: crates/lib/src/token/token.rs - Function: verifytokenpayment() - Lines: 529–654 (specifically 633–639) Root Cause In verifytokenpayment(), the amount extracted from the parsed SPL transfer instruction is the pre-fee amount (what the sender specifies in the transferchecked instruction). The function passes this raw amount to calculatetokenvalueinlamports() to determine how many lamports the payment is worth. It never subtracts the Token-2022 transfer fee. The fee…

Published by the source

12 Mar 2026, 14:50 UTC

Last modified by the source

12 Mar 2026, 14:50 UTC

Source last checked

26 Oct 2026, 15:42 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-725g-w329-g7qr

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# Patch Next advisory brief: GHSA-725g-w329-g7qr

Advisory: kora-lib: Token-2022 Transfer Fee Not Deducted During Payment Verification
IDs: GHSA-725g-w329-g7qr
Record: https://patchnext.com/advisories/ghsa-725g-w329-g7qr (revision 1, source checked 26 Oct 2026, 15:42 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: kora-lib 2.0.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io kora-lib: affected < 2.0.5; fixed in 2.0.5

## Suggested inspection (read-only)
- crates.io kora-lib: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on kora-lib.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-725g-w329-g7qr (GitHub-reviewed advisory GHSA-725g-w329-g7qr lists affected ranges: crates.io kora-lib >=0 <2.0.5)

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