CVE-2026-79977 (GCVE-0-2026-79977)
Vulnerability from cvelistv5 – Published: 2026-10-23 19:56 – Updated: 2026-10-23 19:56
VLAI
EPSS
VEX
Title
WireGuard peer endpoint learned from unauthenticated transport-data messages allows off-path tunnel hijack in Zephyr
Summary
The WireGuard VPN service in subsys/net/lib/wireguard/wg.c updated the peer endpoint from a message it could not authenticate. In handle_transport_data(), when the 32-bit receiver index of an incoming transport-data message matched no session, the code both scheduled a new handshake and copied the datagram's source address into peer->endpoint with memcpy(&peer->endpoint, peer_addr, sizeof(peer->endpoint)). Because the receiver index is unknown, there is no key with which such a message could be verified, so the address written into peer->endpoint is entirely attacker-supplied. Every other endpoint update in the implementation happens only after authentication — after the Noise handshake in handle_handshake_init(), or after AEAD decryption plus the anti-replay check in wg_process_data_message().
The WireGuard listener is registered with net_udp_register() using no remote address or port filter and defaults to UDP port 51820 (CONFIG_WIREGUARD_PORT), and wg_ctrl_recv() resolves the peer by interface rather than by any cryptographic identity. Any host able to send a UDP datagram to that port can therefore reach the defect off-path, with no need to observe legitimate traffic: a 16-byte datagram carrying the transport-data type, zeroed reserved bytes and an arbitrary receiver index is sufficient. The vulnerable branch runs whenever the peer has neither a valid handshake nor a current keypair — the state at boot and after a session expires.
A single spoofed datagram redirects peer->endpoint to an address of the attacker's choosing, and all subsequent handshake initiations, keepalives and encrypted data packets are sent there. The legitimate peer never receives the initiations and so never re-authenticates, and nothing resets the endpoint afterwards, leaving the tunnel persistently unusable on devices whose peer does not initiate handshakes itself. The attacker can also relay the redirected initiations to the real peer to place itself in the path of the tunnel, observing ciphertext and traffic metadata and selectively dropping packets. WireGuard's end-to-end cryptography still prevents decryption or forgery of tunnel content, so the impact is loss of availability plus limited confidentiality, not key compromise.
The fix removes the endpoint learning from this path entirely: the stale-session recovery is kept, but the handshake is sent only to an endpoint learnt from an authenticated message, falling back to the configured cfg_endpoint, and the message is dropped when neither is known. CONFIG_WIREGUARD is marked experimental and is not enabled by default.
Severity
8.2 (High)
Assigner
References
2 references
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| zephyrproject | zephyr |
Affected:
4.4.0 , ≤ 4.4.2
(semver)
|
guessed |
{
"containers": {
"cna": {
"affected": [
{
"collectionURL": "https://github.com/zephyrproject-rtos/zephyr",
"defaultStatus": "unaffected",
"packageName": "zephyr",
"product": "zephyr",
"programRoutines": [
{
"name": "handle_transport_data"
}
],
"vendor": "zephyrproject",
"versions": [
{
"lessThanOrEqual": "4.4.2",
"status": "affected",
"version": "4.4.0",
"versionType": "semver"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "The WireGuard VPN service in subsys/net/lib/wireguard/wg.c updated the peer endpoint from a message it could not authenticate. In handle_transport_data(), when the 32-bit receiver index of an incoming transport-data message matched no session, the code both scheduled a new handshake and copied the datagram\u0027s source address into peer-\u003eendpoint with memcpy(\u0026peer-\u003eendpoint, peer_addr, sizeof(peer-\u003eendpoint)). Because the receiver index is unknown, there is no key with which such a message could be verified, so the address written into peer-\u003eendpoint is entirely attacker-supplied. Every other endpoint update in the implementation happens only after authentication \u2014 after the Noise handshake in handle_handshake_init(), or after AEAD decryption plus the anti-replay check in wg_process_data_message().\n\nThe WireGuard listener is registered with net_udp_register() using no remote address or port filter and defaults to UDP port 51820 (CONFIG_WIREGUARD_PORT), and wg_ctrl_recv() resolves the peer by interface rather than by any cryptographic identity. Any host able to send a UDP datagram to that port can therefore reach the defect off-path, with no need to observe legitimate traffic: a 16-byte datagram carrying the transport-data type, zeroed reserved bytes and an arbitrary receiver index is sufficient. The vulnerable branch runs whenever the peer has neither a valid handshake nor a current keypair \u2014 the state at boot and after a session expires.\n\nA single spoofed datagram redirects peer-\u003eendpoint to an address of the attacker\u0027s choosing, and all subsequent handshake initiations, keepalives and encrypted data packets are sent there. The legitimate peer never receives the initiations and so never re-authenticates, and nothing resets the endpoint afterwards, leaving the tunnel persistently unusable on devices whose peer does not initiate handshakes itself. The attacker can also relay the redirected initiations to the real peer to place itself in the path of the tunnel, observing ciphertext and traffic metadata and selectively dropping packets. WireGuard\u0027s end-to-end cryptography still prevents decryption or forgery of tunnel content, so the impact is loss of availability plus limited confidentiality, not key compromise.\n\nThe fix removes the endpoint learning from this path entirely: the stale-session recovery is kept, but the handshake is sent only to an endpoint learnt from an authenticated message, falling back to the configured cfg_endpoint, and the message is dropped when neither is known. CONFIG_WIREGUARD is marked experimental and is not enabled by default."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 8.2,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H",
"version": "3.1"
},
"format": "CVSS"
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-306",
"description": "auth",
"lang": "en",
"type": "CWE"
},
{
"cweId": "CWE-346",
"description": "auth",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-10-23T19:56:13.873Z",
"orgId": "e2e69745-5e70-4e92-8431-deb5529a81ad",
"shortName": "zephyr"
},
"references": [
{
"name": "Fix commit",
"tags": [
"patch"
],
"url": "https://github.com/zephyrproject-rtos/zephyr/commit/cbaaf3e9dbe08be21f01bd23142e1ffe91fd4db6"
},
{
"name": "GHSA-w8h4-r8m3-rf5j",
"url": "https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-w8h4-r8m3-rf5j"
}
],
"title": "WireGuard peer endpoint learned from unauthenticated transport-data messages allows off-path tunnel hijack in Zephyr",
"x_generator": {
"engine": "cvelib 1.8.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "e2e69745-5e70-4e92-8431-deb5529a81ad",
"assignerShortName": "zephyr",
"cveId": "CVE-2026-79977",
"datePublished": "2026-10-23T19:56:13.873Z",
"dateReserved": "2026-08-25T16:06:28.969Z",
"dateUpdated": "2026-10-23T19:56:13.873Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-79977",
"date": "2026-10-25",
"epss": "0.00168",
"percentile": "0.05995"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"collectionURL": "https://github.com/zephyrproject-rtos/zephyr",
"defaultStatus": "unaffected",
"packageName": "zephyr",
"product": "zephyr",
"programRoutines": [
{
"name": "handle_transport_data"
}
],
"vendor": "zephyrproject",
"versions": [
{
"lessThanOrEqual": "4.4.2",
"status": "affected",
"version": "4.4.0",
"versionType": "semver"
}
]
}
],
"source": "vulnerabilities@zephyrproject.org"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "The WireGuard VPN service in subsys/net/lib/wireguard/wg.c updated the peer endpoint from a message it could not authenticate. In handle_transport_data(), when the 32-bit receiver index of an incoming transport-data message matched no session, the code both scheduled a new handshake and copied the datagram\u0027s source address into peer-\u003eendpoint with memcpy(\u0026peer-\u003eendpoint, peer_addr, sizeof(peer-\u003eendpoint)). Because the receiver index is unknown, there is no key with which such a message could be verified, so the address written into peer-\u003eendpoint is entirely attacker-supplied. Every other endpoint update in the implementation happens only after authentication \u2014 after the Noise handshake in handle_handshake_init(), or after AEAD decryption plus the anti-replay check in wg_process_data_message().\n\nThe WireGuard listener is registered with net_udp_register() using no remote address or port filter and defaults to UDP port 51820 (CONFIG_WIREGUARD_PORT), and wg_ctrl_recv() resolves the peer by interface rather than by any cryptographic identity. Any host able to send a UDP datagram to that port can therefore reach the defect off-path, with no need to observe legitimate traffic: a 16-byte datagram carrying the transport-data type, zeroed reserved bytes and an arbitrary receiver index is sufficient. The vulnerable branch runs whenever the peer has neither a valid handshake nor a current keypair \u2014 the state at boot and after a session expires.\n\nA single spoofed datagram redirects peer-\u003eendpoint to an address of the attacker\u0027s choosing, and all subsequent handshake initiations, keepalives and encrypted data packets are sent there. The legitimate peer never receives the initiations and so never re-authenticates, and nothing resets the endpoint afterwards, leaving the tunnel persistently unusable on devices whose peer does not initiate handshakes itself. The attacker can also relay the redirected initiations to the real peer to place itself in the path of the tunnel, observing ciphertext and traffic metadata and selectively dropping packets. WireGuard\u0027s end-to-end cryptography still prevents decryption or forgery of tunnel content, so the impact is loss of availability plus limited confidentiality, not key compromise.\n\nThe fix removes the endpoint learning from this path entirely: the stale-session recovery is kept, but the handshake is sent only to an endpoint learnt from an authenticated message, falling back to the configured cfg_endpoint, and the message is dropped when neither is known. CONFIG_WIREGUARD is marked experimental and is not enabled by default."
}
],
"id": "CVE-2026-79977",
"lastModified": "2026-10-23T20:17:27.523",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 8.2,
"baseSeverity": "HIGH",
"confidentialityImpact": "LOW",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H",
"version": "3.1"
},
"exploitabilityScore": 3.9,
"impactScore": 4.2,
"source": "vulnerabilities@zephyrproject.org",
"type": "Secondary"
}
]
},
"published": "2026-10-23T20:17:27.523",
"references": [
{
"source": "vulnerabilities@zephyrproject.org",
"url": "https://github.com/zephyrproject-rtos/zephyr/commit/cbaaf3e9dbe08be21f01bd23142e1ffe91fd4db6"
},
{
"source": "vulnerabilities@zephyrproject.org",
"url": "https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-w8h4-r8m3-rf5j"
}
],
"sourceIdentifier": "vulnerabilities@zephyrproject.org",
"vulnStatus": "Received",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-306"
},
{
"lang": "en",
"value": "CWE-346"
}
],
"source": "vulnerabilities@zephyrproject.org",
"type": "Secondary"
}
]
}
}
}
}
Loading…
Loading…
Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
Loading timeline…
Loading…
Loading…
The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Loading…
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.