CVE-2026-72019 (GCVE-0-2026-72019)
Vulnerability from cvelistv5 – Published: 2026-08-15 05:51 – Updated: 2026-08-19 16:35
VLAI
EPSS
VEX
Title
macsec: don't read an unset MAC header in macsec_encrypt()
Summary
In the Linux kernel, the following vulnerability has been resolved:
macsec: don't read an unset MAC header in macsec_encrypt()
macsec_encrypt() reads the Ethernet header via eth_hdr(skb)
(skb->head + skb->mac_header) to memmove() the 12 source/destination MAC
bytes forward and make room for the SecTAG.
On the AF_PACKET SOCK_RAW + PACKET_QDISC_BYPASS transmit path the skb
reaches the macsec ndo_start_xmit() with the MAC header unset, so
eth_hdr(skb) resolves to skb->head + (u16)~0 and the read is out of
bounds: a 12-byte heap over-read that is also emitted on the wire as the
frame's outer source/destination MAC. KASAN reports a slab-out-of-bounds
read in macsec_start_xmit() on 6.0; on current mainline a CONFIG_DEBUG_NET
build flags it as an unset mac header in skb_mac_header().
On the TX path the L2 header is at skb->data, so use skb_eth_hdr(), added
by commit 96cc4b69581d ("macvlan: do not assume mac_header is set in
macvlan_broadcast()") for exactly this purpose.
Severity
7.3 (High)
Assigner
References
8 references
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
c09440f7dcb304002dfced8c0fea289eb25f2da0 , < b6cec6187b8632423cd99a94fd5e5ba165fa2a33
(git)
Affected: c09440f7dcb304002dfced8c0fea289eb25f2da0 , < 3adea1b1c04b57e08a5c12a1f42483760581ce61 (git) Affected: c09440f7dcb304002dfced8c0fea289eb25f2da0 , < dc9ffa1905e72f026d080880a2e4cfc42aa91000 (git) Affected: c09440f7dcb304002dfced8c0fea289eb25f2da0 , < f21fa533a3ed15ada74106aac4b9ddd078fc6b7a (git) Affected: c09440f7dcb304002dfced8c0fea289eb25f2da0 , < e17a42199824973cd8212e95b21ffadf4114a21b (git) Affected: c09440f7dcb304002dfced8c0fea289eb25f2da0 , < 2cf10d042562283ff4ae97c02d0993d4f1b5ea29 (git) Affected: c09440f7dcb304002dfced8c0fea289eb25f2da0 , < c39087ad0b97fc11a3b058dfc8db9fd370762cb9 (git) Affected: c09440f7dcb304002dfced8c0fea289eb25f2da0 , < f5089008f90c0a7c5520dff3934e0af00adf322d (git) |
guessed | |
| Linux | Linux |
Affected:
4.6
Unaffected: 0 , < 4.6 (semver) Unaffected: 5.10.265 , ≤ 5.10.* (semver) Unaffected: 5.15.216 , ≤ 5.15.* (semver) Unaffected: 6.1.178 , ≤ 6.1.* (semver) Unaffected: 6.6.145 , ≤ 6.6.* (semver) Unaffected: 6.12.97 , ≤ 6.12.* (semver) Unaffected: 6.18.40 , ≤ 6.18.* (semver) Unaffected: 7.1.5 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix) |
guessed |
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmacsec: don\u0027t read an unset MAC header in macsec_encrypt()\n\nmacsec_encrypt() reads the Ethernet header via eth_hdr(skb)\n(skb-\u003ehead + skb-\u003emac_header) to memmove() the 12 source/destination MAC\nbytes forward and make room for the SecTAG.\n\nOn the AF_PACKET SOCK_RAW + PACKET_QDISC_BYPASS transmit path the skb\nreaches the macsec ndo_start_xmit() with the MAC header unset, so\neth_hdr(skb) resolves to skb-\u003ehead + (u16)~0 and the read is out of\nbounds: a 12-byte heap over-read that is also emitted on the wire as the\nframe\u0027s outer source/destination MAC. KASAN reports a slab-out-of-bounds\nread in macsec_start_xmit() on 6.0; on current mainline a CONFIG_DEBUG_NET\nbuild flags it as an unset mac header in skb_mac_header().\n\nOn the TX path the L2 header is at skb-\u003edata, so use skb_eth_hdr(), added\nby commit 96cc4b69581d (\"macvlan: do not assume mac_header is set in\nmacvlan_broadcast()\") for exactly this purpose."
}
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"value": "AV:L - The bug is reached only via local AF_PACKET SOCK_RAW transmit with PACKET_QDISC_BYPASS to a macsec netdev; it is a TX-only ndo_start_xmit path, not reachable from remote network packet reception.\nAC:L - An attacker fully controls the trigger: create a raw packet socket with a specific ethertype, enable PACKET_QDISC_BYPASS, and send a frame on a configured macsec interface with protect_frames enabled.\nPR:L - Exploitation requires CAP_NET_RAW for AF_PACKET and CAP_NET_ADMIN to create/configure a macsec netdev and TX SA keys; both are obtainable by an unprivileged user inside a user namespace with delegated capabilities.\nUI:N - No victim interaction is required; the attacker sends crafted frames directly through the vulnerable transmit path without any action from another user or administrator.\nS:U - Impact is confined to kernel heap disclosure and possible kernel crash on the same host; it does not cross a VM, container, or IOMMU security boundary to affect a separate authority.\nC:H - eth_hdr(skb) performs a 12-byte slab out-of-bounds heap read when mac_header is unset; the leaked kernel memory is copied into the transmitted frame\u0027s source/destination MAC fields, disclosing sensitive heap contents.\nI:L - The memmove in macsec_encrypt() overwrites the outgoing frame\u0027s 12-byte Ethernet addresses with leaked heap data, causing unauthorized modification of transmitted packet contents without arbitrary kernel memory writes.\nA:H - Reading from skb-\u003ehead plus unset mac_header offset 65535 causes a slab out-of-bounds access that KASAN flags and can page-fault into a kernel oops or panic when macsec_encrypt() runs on affected builds."
}
]
}
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"providerMetadata": {
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"title": "macsec: don\u0027t read an unset MAC header in macsec_encrypt()",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmacsec: don\u0027t read an unset MAC header in macsec_encrypt()\n\nmacsec_encrypt() reads the Ethernet header via eth_hdr(skb)\n(skb-\u003ehead + skb-\u003emac_header) to memmove() the 12 source/destination MAC\nbytes forward and make room for the SecTAG.\n\nOn the AF_PACKET SOCK_RAW + PACKET_QDISC_BYPASS transmit path the skb\nreaches the macsec ndo_start_xmit() with the MAC header unset, so\neth_hdr(skb) resolves to skb-\u003ehead + (u16)~0 and the read is out of\nbounds: a 12-byte heap over-read that is also emitted on the wire as the\nframe\u0027s outer source/destination MAC. KASAN reports a slab-out-of-bounds\nread in macsec_start_xmit() on 6.0; on current mainline a CONFIG_DEBUG_NET\nbuild flags it as an unset mac header in skb_mac_header().\n\nOn the TX path the L2 header is at skb-\u003edata, so use skb_eth_hdr(), added\nby commit 96cc4b69581d (\"macvlan: do not assume mac_header is set in\nmacvlan_broadcast()\") for exactly this purpose."
}
],
"id": "CVE-2026-72019",
"lastModified": "2026-08-19T17:20:57.200",
"metrics": {
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"attackComplexity": "LOW",
"attackVector": "LOCAL",
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"baseScore": 7.3,
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"confidentialityImpact": "HIGH",
"integrityImpact": "LOW",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H",
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},
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"published": "2026-08-15T06:21:00.790",
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},
{
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"url": "https://git.kernel.org/stable/c/f21fa533a3ed15ada74106aac4b9ddd078fc6b7a"
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}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-08-17T14:55:13+00:00",
"cve": "CVE-2026-72019",
"id": "CVE-2026-72019",
"initial_release_date": "2026-08-15T00:00:00+00:00",
"product_status:known_affected": "260",
"product_status:known_not_affected": "14",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: macsec: don\u0027t read an unset MAC header in macsec_encrypt()",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72019.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "moderate",
"current_release_date": "2026-10-03T00:30:37Z",
"cve": "CVE-2026-72019",
"id": "CVE-2026-72019",
"initial_release_date": "2026-08-27T00:24:31Z",
"product_status:known_affected": "358",
"product_status:known_not_affected": "6",
"product_status:recommended": "145",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-72019",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-72019.json",
"version": "6"
}
}
}
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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.
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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.
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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.
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