CVE-2026-68296
In the Linux kernel, the following vulnerability has been resolved:
net: gre: fix lltx regression for GRE tunnels with SEQ/CSUM
Before commit 00d066a4d4ed ("netdev_features: convert NETIF_F_LLTX to dev->lltx"), NETIF_F_LLTX was set unconditionally in both __gre_tunnel_init() and ip6gre_tnl_init_features() alongside GRE_FEATURES:
When that commit converted NETIF_F_LLTX to the dev->lltx flag, it placed 'dev->lltx = true' after the SEQ/CSUM early returns instead of before them. This causes GRE/GRETAP/ip6gre tunnels with SEQ or CSUM+encap to lose lockless TX, reintroducing _xmit_lock acquisition around their ndo_start_xmit. Since GRE xmit re-enters the stack via ip_tunnel_xmit(), holding _xmit_lock risks ABBA deadlock with the underlay device.
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Fix by moving dev->lltx = true before the early returns in both functions, restoring the original unconditional behavior.
Detalles técnicos trazas, registros y código del informe original
dev->features |= GRE_FEATURES | NETIF_F_LLTX;
CPU0 CPU1
---- ----
lock(&qdisc_xmit_lock_key#6);
lock(&qdisc_xmit_lock_key#3);
lock(&qdisc_xmit_lock_key#6);
lock(&qdisc_xmit_lock_key#3);CVSS
NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.21%
- Percentil entre todas las CVEs puntuadas: 10
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
JSON original (NVD)
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{
"id": "CVE-2026-68296",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "00d066a4d4edbe559ba6c35153da71d4b2b8a383",
"lessThan": "9f948e9aede9678f4103457daf2bc9dd54c65a06",
"versionType": "git"
},
{
"status": "affected",
"version": "00d066a4d4edbe559ba6c35153da71d4b2b8a383",
"lessThan": "15a1c5f2ed2eeb3daad8d5766fd506aeda4710f3",
"versionType": "git"
},
{
"status": "affected",
"version": "00d066a4d4edbe559ba6c35153da71d4b2b8a383",
"lessThan": "2bffe379023512d280337c70faeb6a8cc435db5e",
"versionType": "git"
},
{
"status": "affected",
"version": "00d066a4d4edbe559ba6c35153da71d4b2b8a383",
"lessThan": "675ed582c1aa4d919dd535490de08c015005c653",
"versionType": "git"
}
],
"programFiles": [
"net/ipv4/ip_gre.c",
"net/ipv6/ip6_gre.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.12"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.12",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.12.101",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.42",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.6",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/ipv4/ip_gre.c",
"net/ipv6/ip6_gre.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-08-10T13:20:19.053",
"references": [
{
"url": "https://git.kernel.org/stable/c/15a1c5f2ed2eeb3daad8d5766fd506aeda4710f3",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/2bffe379023512d280337c70faeb6a8cc435db5e",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/675ed582c1aa4d919dd535490de08c015005c653",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/9f948e9aede9678f4103457daf2bc9dd54c65a06",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: gre: fix lltx regression for GRE tunnels with SEQ/CSUM\n\nBefore commit 00d066a4d4ed (\"netdev_features: convert NETIF_F_LLTX to\ndev->lltx\"), NETIF_F_LLTX was set unconditionally in both\n__gre_tunnel_init() and ip6gre_tnl_init_features() alongside\nGRE_FEATURES:\n\n dev->features |= GRE_FEATURES | NETIF_F_LLTX;\n\nWhen that commit converted NETIF_F_LLTX to the dev->lltx flag, it\nplaced 'dev->lltx = true' after the SEQ/CSUM early returns instead\nof before them. This causes GRE/GRETAP/ip6gre tunnels with SEQ or\nCSUM+encap to lose lockless TX, reintroducing _xmit_lock acquisition\naround their ndo_start_xmit. Since GRE xmit re-enters the stack via\nip_tunnel_xmit(), holding _xmit_lock risks ABBA deadlock with the\nunderlay device.\n\n CPU0 CPU1\n ---- ----\n lock(&qdisc_xmit_lock_key#6);\n lock(&qdisc_xmit_lock_key#3);\n lock(&qdisc_xmit_lock_key#6);\n lock(&qdisc_xmit_lock_key#3);\n\nFix by moving dev->lltx = true before the early returns in both\nfunctions, restoring the original unconditional behavior."
}
],
"lastModified": "2026-08-17T05:18:32.323",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}