CVE-2026-39880Public exploitNetwork attack vector

Subscription limit bypass via non-atomic device registration

Published Apr 8, 2026 · Updated Apr 8, 2026

Race condition in Remnawave Backend before 2.7.5 allows remote authenticated users to exceed configured HWID device limits. HWID registration counts a user's devices and later inserts a new record without transactional locking or an atomic limit check, so concurrent requests can all pass the same stale count. A subscription holder can issue parallel requests with distinct HWIDs, register excess devices, and consume traffic beyond the configured subscription policy.

CVSS severity5.0
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in Remnawave Backend before 2.7.5 allows remote authenticated users to exceed configured HWID device limits. HWID registration counts a user's devices and later inserts a new record without transactional locking or an atomic limit check, so concurrent requests can all pass the same stale count. A subscription holder can issue parallel requests with distinct HWIDs, register excess devices, and consume traffic beyond the configured subscription policy.

The record

CVE
CVE-2026-39880
Published
Apr 8, 2026
Updated
Apr 8, 2026
Vendor
Remnawave
Product
Remnawave Backend
Classifications
CWE-362, T1496
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.7.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Remnawave · Remnawave Backendversion=< 2.7.5

Published CVSS scores

4.9NIST NVDCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:L
5.0GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
T1496Resource Hijacking

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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