CVE-2026-88255

MEDIUMPre-NVD 6.36.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 67% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 4 sources updated this week
6.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.3Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Improper Validation of Unsafe Equivalence in Input in ZenHive mpp allows an unauthenticated remote client to pass the Tempo duplicate-submission gate twice with one signed transaction.

MPP.Methods.Tempo reserves the pre-broadcast dedup slot on the caller-supplied hex in reserve_hash_atomic/2, keyed through store_key/1 on tx.raw rather than on a canonical form of the transaction. The deserializer stores the caller's hex verbatim and accepts both recovery-id encodings, so one signed transaction submitted once with v=27 and once with v=0 yields two distinct reserve keys, and both pass the reserve and reach the broadcast path. The plug-level credential replay store is deliberately carved out for tempo in lib/mpp/replay.ex, leaving this reserve as the only gate, and the post-broadcast mark writes the canonical hash key that the raw-keyed reserve never reads.

What the duplicate submission yields depends on the node: a nonce-reuse rejection fails closed, while a node that answers with the canonical hash for an already-known transaction returns a second valid Payment-Receipt for a single on-chain payment.

This issue affects mpp: from 0.2.0 before 0.16.2.

CVSS v3
6.3
EG Score
6.3(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity63% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
33%
KEV
Not listed

Published

September 16, 2026

Last Modified

September 16, 2026

Advisory Details (5)

Auto-updated Sep 16, 2026
Patch available. Sources: github, github_commit.
github_commit

commit e12bd4a1cea2 (ZenHive/mpp)

Fix landed in ZenHive/mpp commit e12bd4a1cea2 — awaiting tagged release

https://github.com/ZenHive/mpp/commit/e12bd4a1cea2e97c2a01fc059c48e5594a7b4a43
github_commit

commit f8904666061f (ZenHive/mpp)

Fix landed in ZenHive/mpp commit f8904666061f — awaiting tagged release

https://github.com/ZenHive/mpp/commit/f8904666061fbab695874856d8fcd02c471dfe1b
generic

Vulnerability Database - OSV

https://osv.dev/vulnerability/EEF-CVE-2026-88255
generic

CVE-2026-88255

https://cna.erlef.org/cves/CVE-2026-88255.html
github Patch Available

Tempo pre-broadcast dedup reserve keyed on the caller-supplied transaction encoding — a non-canonical re-encoding of one signed transaction reserves a second slot · Advisory · ZenHive/mpp · GitHub

https://github.com/ZenHive/mpp/security/advisories/GHSA-8x7x-5j8g-8hcx

Vendor Advisories for CVE-2026-88255(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
Hex(1)
PackageVulnerable rangeFixed inDependents
mpp0.10.0 ... 0.9.0 (21 versions)0.16.2—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 15× in last 7d / 15× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-18 17:22 UTCEG score recompute
  3. 2026-09-18 17:22 UTCGHSA enrichment
  4. 2026-09-17 19:32 UTCEPSS rescore
  5. 2026-09-17 19:12 UTCGHSA enrichment
  6. 2026-09-16 21:01 UTCGHSA enrichment
  7. 2026-09-16 15:25 UTCEG score recompute
  8. 2026-09-16 15:25 UTCGHSA enrichment
  9. 2026-09-16 15:01 UTCEG score recompute
  10. 2026-09-16 15:01 UTCGHSA enrichment
  11. 2026-09-16 14:09 UTCEPSS rescore
  12. 2026-09-16 09:31 UTCEG score recompute
  13. 2026-09-16 09:31 UTCGHSA enrichment
  14. 2026-09-16 08:27 UTCEG score recompute
  15. 2026-09-16 08:26 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-88255?
CVE-2026-88255 is a medium vulnerability published on September 16, 2026. Improper Validation of Unsafe Equivalence in Input in ZenHive mpp allows an unauthenticated remote client to pass the Tempo duplicate-submission gate twice with one signed transaction. MPP.Methods.Tempo reserves the pre-broadcast dedup slot on the caller-supplied hex in reservehashatomic/2, keyed…
When was CVE-2026-88255 disclosed?
CVE-2026-88255 was first published in the National Vulnerability Database on September 16, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-88255 actively exploited?
CVE-2026-88255 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 66.6% of all scored CVEs.
What is the CVSS score of CVE-2026-88255?
CVE-2026-88255 has a CVSS v3 base score of 6.3 (NVD).
How do I remediate CVE-2026-88255?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-88255, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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