macsec: don't read an unset MAC header in macsec_encrypt()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-72019
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-15 06:21:00 UTC
Updated2026-08-17 06:17:59 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 7.3 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H

EPSS: 0.001670000 probability, percentile 0.064760000 (date 2026-08-19)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.3HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H
3.1CNADECLARED7.3HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
Low
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected c09440f7dcb304002dfced8c0fea289eb25f2da0 b6cec6187b8632423cd99a94fd5e5ba165fa2a33 git Not specified
CNA Linux Linux affected c09440f7dcb304002dfced8c0fea289eb25f2da0 3adea1b1c04b57e08a5c12a1f42483760581ce61 git Not specified
CNA Linux Linux affected c09440f7dcb304002dfced8c0fea289eb25f2da0 dc9ffa1905e72f026d080880a2e4cfc42aa91000 git Not specified
CNA Linux Linux affected c09440f7dcb304002dfced8c0fea289eb25f2da0 f21fa533a3ed15ada74106aac4b9ddd078fc6b7a git Not specified
CNA Linux Linux affected c09440f7dcb304002dfced8c0fea289eb25f2da0 e17a42199824973cd8212e95b21ffadf4114a21b git Not specified
CNA Linux Linux affected c09440f7dcb304002dfced8c0fea289eb25f2da0 2cf10d042562283ff4ae97c02d0993d4f1b5ea29 git Not specified
CNA Linux Linux affected c09440f7dcb304002dfced8c0fea289eb25f2da0 c39087ad0b97fc11a3b058dfc8db9fd370762cb9 git Not specified
CNA Linux Linux affected c09440f7dcb304002dfced8c0fea289eb25f2da0 f5089008f90c0a7c5520dff3934e0af00adf322d git Not specified
CNA Linux Linux affected 4.6 Not specified
CNA Linux Linux unaffected 4.6 semver Not specified
CNA Linux Linux unaffected 5.10.265 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.216 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.178 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.145 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.97 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.40 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.5 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/e17a42199824973cd8212e95b21ffadf4114a21b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/c39087ad0b97fc11a3b058dfc8db9fd370762cb9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/dc9ffa1905e72f026d080880a2e4cfc42aa91000 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f5089008f90c0a7c5520dff3934e0af00adf322d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f21fa533a3ed15ada74106aac4b9ddd078fc6b7a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/3adea1b1c04b57e08a5c12a1f42483760581ce61 https://git.kernel.org/stable/c/3adea1b1c04b57e08a5c12a1f42483760581ce61 git.kernel.org
git.kernel.org/stable/c/b6cec6187b8632423cd99a94fd5e5ba165fa2a33 https://git.kernel.org/stable/c/b6cec6187b8632423cd99a94fd5e5ba165fa2a33 git.kernel.org
git.kernel.org/stable/c/2cf10d042562283ff4ae97c02d0993d4f1b5ea29 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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