vciy

CVE-2026-13734

INDEX BUILT · 2026-09-20

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Zephyr WireGuard mutates peer state before anti-replay check, enabling capture-replay endpoint hijack

CVE-2026-137343 of 4 sources documented this
16

rank 16 = 0 + 16 + 0 + 0 + 0

rank@v1 · backlog

Someone is already using it

CISA KEV catalog · public proof-of-concept · FIRST EPSS

EPSS 0.00248  ·  without this subject the record ranks 16

What it costs you if it fires

NVD CVSS base score, then the CNA's own

CVSS 6.5, from the CNA  ·  without this subject the record ranks 0

It is getting worse, not staying still

FIRST EPSS series, rescorings and bad loads removed

no persisting rise in 365 days  ·  without this subject the record ranks 16

How much of the world it touches

NVD CPE configurations

0 products in the CPE ranges  ·  without this subject the record ranks 16

Someone else already set the date

CISA KEV remediation due date

no CISA due date  ·  without this subject the record ranks 16

Unaudited dollar value2 of 3 inputs carry a receipt
Exposure$8,880over the next 30 days, if this record is yours
Movementnot heldno dated series to read a change from
Basisassumeda published average, not your estate

$8,880 = $4.99M incident cost x 0.7179585840212677 exposure x 0.00248 likelihood

udv@v1 · unaudited · wrong for you until you say what you run

$4.99M is the cost of a breach that happened, from IBM Cost of a Data Breach Report 2026, global average. It is not the value of any asset of yours. That average already covers breaches of every severity, so scaling it by exposure understates a partial-impact record. That is an assumption, not a measurement. Your own asset value goes in the decision record.

Hindsight · the state

0.00248EPSSNOT IN KEVas of 2026-09-20
Severity6.5 MEDIUMreceipt
Harmunauthenticated · networkreceipt
Exploitationnone in held sources
Defensefix version namedreceipt
Movementone observationreceipt
SINGLE READINGOne observation held. There is no shape yet. arc-rules@v1

Foresight · where to check next

No weakness class or product neighbourhood is held for this record, so this index cannot name anywhere to check next. That is an absence in the record, not a finding about the software.

Color is a claim, not decoration:the hostile worldthe defenseno signal

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Reachnetwork-reachable · no privileges required · no user interaction · high attack complexityreceipt
ImpactPartial integrity loss; complete availability lossreceipt
Scored fromCVSS v3.1 · the CNA's vectorreceipt
Weakness classCWE-294 Authentication Bypass by Capture-replayreceipt
Published consequencesCWE-294: Access Control: Gain Privileges or Assume Identity[email protected]

CISA KEV & Federal Remediation Deadline from the record and CISA

The fix, and how long it's been waiting.

Fixed in4.4.2receipt
Patch available sinceNo dated patch-availability record in held sources. The index holds reference URLs without dates and only the current revision of the CVE record, so the day a fix first existed cannot be derived. Only the versions it landed in.

Exploit Status & Known PoCs a ladder, not a score

Current rung: Nothing observed in held sources.

  • RUNG 1Nothing observed in held sources
  • RUNG 2Proof-of-concept published
  • RUNG 3Exploited in the wild · CISA KEV listed
  • RUNG 4Ransomware campaign use known

Authority who says so

CVSS, the CNA6.5 MEDIUMreceipt
Exploit probability0.00248 · top 84% of all CVEsreceipt
Assigned byzephyrreceipt
Recorded changes1 · last 19 Sep 2026derived

Affected & Fixed Versions as published

Affected productzephyrproject zephyrreceipt
Fixed in4.4.2receipt

A rung lights from a row in the index, never from an assessment. "Held sources" is the true scope of the claim: this index reads the CVE record, NVD, CISA KEV, FIRST's EPSS and public proof-of-concept repositories, and it does not observe attacks.

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Attack path

Unauthenticated network requestno credentials, no interactionzephyrproject zephyrCWE-294 weaknessAvailability lossA:Hexploits CWE-294data compromise

What it is stated by the CNA

Zephyr's WireGuard VPN data-plane receive handler wg_process_data_message() in subsys/net/lib/wireguard/wg_crypto.c validated the anti-replay counter too late. After AEAD decryption of a MESSAGE_TRANSPORT_DATA packet succeeded, the code committed several peer-state changes — update_peer_addr() (endpoint roaming update), the keypair->last_rx/peer->last_rx liveness timers, and keypair_update() (promote next→current and destroy the previous keypair) — and only afterward called wg_check_replay(). receipt

Read the rest of the CNA's description

On a replayed packet the replay check returned -EINVAL, but none of the preceding mutations were rolled back. The AEAD tag authenticates content but not freshness, so a replayed-but-authentic transport packet decrypts correctly. An attacker who captures one valid ciphertext off the wire (an on-path or shared-medium observer) can re-inject it from an arbitrary spoofed source address. Reaching the handler requires no credentials: it is driven directly from inbound UDP datagrams via the dispatch in subsys/net/lib/wireguard/wg.c. Because the state mutations committed before the replay check, the replay repoints the peer endpoint to the attacker-chosen source address (roaming hijack), redirecting the victim's subsequent outbound tunnel traffic until the legitimate peer's next packet re-corrects it; it also prematurely destroys the previous keypair and refreshes the RX liveness timer. The tunnel payload stays encrypted under the session keypair, so this is an integrity/availability impact (traffic redirection and session disruption), not payload disclosure. The fix moves wg_check_replay() to immediately after a successful decrypt, before any peer-state mutation, matching the WireGuard specification and the Linux reference implementation.

NVD's analysis a second authority

weakness
CWE-294
also scored by
[email protected] 6.5 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H

check it yourself github.com github.com receipt

Movement

Only one observation of this value is held, so there is no movement to show yet.

The full biography

Published2026-08-28Index as of2026-08-29

The record had been public for 1 day when this index was last written.

Published 2026-08-28 receipt · Index as of 2026-08-29 derived

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