VulnerabilityAnalyzed

CVE-2026-73136

Authentication Bypass by Capture-replay in ZenHive mpp allows an unauthenticated third party to obtain paid resources by replaying a transfer settled by an unrelated payer.

HIGH 8.2EPSS 0.42%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.42%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

Authentication Bypass by Capture-replay in ZenHive mpp allows an unauthenticated third party to obtain paid resources by replaying a transfer settled by an unrelated payer. MPP.Methods.Tempo normally binds a settled TIP-20 TransferWithMemo to the specific challenge under verification through an attribution nonce carried in the memo. When a static "memo" is configured in method_config, check_matched_memo_binding/3 returns the match unconditionally and that binding is skipped, leaving only token, recipient, amount and the static memo value to match on. The static memo is echoed in every unauthenticated 402 response and Tempo transfers are public, so an attacker can take any matching transfer paid by a legitimate customer, request a fresh challenge for the same route, and present that transaction hash as a type="hash" credential. The hash path performs no sender or signature check tying the presenter to the wallet that broadcast the transfer. This issue affects mpp: from 0.6.1 before 0.6.4.

CVSS 4.0: 8.2 HIGHCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/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/M
EPSS: 0.42% probability · 35th percentile
CISA KEV: Not listed
Weakness: CWE-294
Affected: zenhive/machine payments protocol
Source: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db

References

https://cna.erlef.org/cves/CVE-2026-73136.htmlThird Party Advisory
https://github.com/ZenHive/mpp/commit/2207d7f456ae14c1d3fcacc6f635bf4f8cee1a34Patch
https://github.com/ZenHive/mpp/security/advisories/GHSA-34g7-vx6g-82mqVendor Advisory
https://osv.dev/vulnerability/EEF-CVE-2026-73136Third Party Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.