CVE-2026-68296 (GCVE-0-2026-68296)
Vulnerability from cvelistv5 – Published: 2026-08-10 12:02 – Updated: 2026-08-17 05:02
VLAI
EPSS
VEX
Title
net: gre: fix lltx regression for GRE tunnels with SEQ/CSUM
Summary
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:
dev->features |= GRE_FEATURES | NETIF_F_LLTX;
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.
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);
Fix by moving dev->lltx = true before the early returns in both
functions, restoring the original unconditional behavior.
Severity
No CVSS data available.
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
00d066a4d4edbe559ba6c35153da71d4b2b8a383 , < 9f948e9aede9678f4103457daf2bc9dd54c65a06
(git)
Affected: 00d066a4d4edbe559ba6c35153da71d4b2b8a383 , < 15a1c5f2ed2eeb3daad8d5766fd506aeda4710f3 (git) Affected: 00d066a4d4edbe559ba6c35153da71d4b2b8a383 , < 2bffe379023512d280337c70faeb6a8cc435db5e (git) Affected: 00d066a4d4edbe559ba6c35153da71d4b2b8a383 , < 675ed582c1aa4d919dd535490de08c015005c653 (git) |
guessed | |
| Linux | Linux |
Affected:
6.12
Unaffected: 0 , < 6.12 (semver) Unaffected: 6.12.101 , ≤ 6.12.* (semver) Unaffected: 6.18.42 , ≤ 6.18.* (semver) Unaffected: 7.1.6 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix) |
guessed |
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/ipv4/ip_gre.c",
"net/ipv6/ip6_gre.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "9f948e9aede9678f4103457daf2bc9dd54c65a06",
"status": "affected",
"version": "00d066a4d4edbe559ba6c35153da71d4b2b8a383",
"versionType": "git"
},
{
"lessThan": "15a1c5f2ed2eeb3daad8d5766fd506aeda4710f3",
"status": "affected",
"version": "00d066a4d4edbe559ba6c35153da71d4b2b8a383",
"versionType": "git"
},
{
"lessThan": "2bffe379023512d280337c70faeb6a8cc435db5e",
"status": "affected",
"version": "00d066a4d4edbe559ba6c35153da71d4b2b8a383",
"versionType": "git"
},
{
"lessThan": "675ed582c1aa4d919dd535490de08c015005c653",
"status": "affected",
"version": "00d066a4d4edbe559ba6c35153da71d4b2b8a383",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/ipv4/ip_gre.c",
"net/ipv6/ip6_gre.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.12"
},
{
"lessThan": "6.12",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.101",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.42",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.6",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.101",
"versionStartIncluding": "6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.42",
"versionStartIncluding": "6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.6",
"versionStartIncluding": "6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
"versionStartIncluding": "6.12",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"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-\u003elltx\"), NETIF_F_LLTX was set unconditionally in both\n__gre_tunnel_init() and ip6gre_tnl_init_features() alongside\nGRE_FEATURES:\n\n dev-\u003efeatures |= GRE_FEATURES | NETIF_F_LLTX;\n\nWhen that commit converted NETIF_F_LLTX to the dev-\u003elltx flag, it\nplaced \u0027dev-\u003elltx = true\u0027 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(\u0026qdisc_xmit_lock_key#6);\n lock(\u0026qdisc_xmit_lock_key#3);\n lock(\u0026qdisc_xmit_lock_key#6);\n lock(\u0026qdisc_xmit_lock_key#3);\n\nFix by moving dev-\u003elltx = true before the early returns in both\nfunctions, restoring the original unconditional behavior."
}
],
"providerMetadata": {
"dateUpdated": "2026-08-17T05:02:32.404Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/9f948e9aede9678f4103457daf2bc9dd54c65a06"
},
{
"url": "https://git.kernel.org/stable/c/15a1c5f2ed2eeb3daad8d5766fd506aeda4710f3"
},
{
"url": "https://git.kernel.org/stable/c/2bffe379023512d280337c70faeb6a8cc435db5e"
},
{
"url": "https://git.kernel.org/stable/c/675ed582c1aa4d919dd535490de08c015005c653"
}
],
"title": "net: gre: fix lltx regression for GRE tunnels with SEQ/CSUM",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-68296",
"datePublished": "2026-08-10T12:02:29.464Z",
"dateReserved": "2026-07-30T09:28:09.380Z",
"dateUpdated": "2026-08-17T05:02:32.404Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-68296",
"date": "2026-09-30",
"epss": "0.00209",
"percentile": "0.09976"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/ipv4/ip_gre.c",
"net/ipv6/ip6_gre.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "9f948e9aede9678f4103457daf2bc9dd54c65a06",
"status": "affected",
"version": "00d066a4d4edbe559ba6c35153da71d4b2b8a383",
"versionType": "git"
},
{
"lessThan": "15a1c5f2ed2eeb3daad8d5766fd506aeda4710f3",
"status": "affected",
"version": "00d066a4d4edbe559ba6c35153da71d4b2b8a383",
"versionType": "git"
},
{
"lessThan": "2bffe379023512d280337c70faeb6a8cc435db5e",
"status": "affected",
"version": "00d066a4d4edbe559ba6c35153da71d4b2b8a383",
"versionType": "git"
},
{
"lessThan": "675ed582c1aa4d919dd535490de08c015005c653",
"status": "affected",
"version": "00d066a4d4edbe559ba6c35153da71d4b2b8a383",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/ipv4/ip_gre.c",
"net/ipv6/ip6_gre.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.12"
},
{
"lessThan": "6.12",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.101",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.42",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.6",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"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-\u003elltx\"), NETIF_F_LLTX was set unconditionally in both\n__gre_tunnel_init() and ip6gre_tnl_init_features() alongside\nGRE_FEATURES:\n\n dev-\u003efeatures |= GRE_FEATURES | NETIF_F_LLTX;\n\nWhen that commit converted NETIF_F_LLTX to the dev-\u003elltx flag, it\nplaced \u0027dev-\u003elltx = true\u0027 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(\u0026qdisc_xmit_lock_key#6);\n lock(\u0026qdisc_xmit_lock_key#3);\n lock(\u0026qdisc_xmit_lock_key#6);\n lock(\u0026qdisc_xmit_lock_key#3);\n\nFix by moving dev-\u003elltx = true before the early returns in both\nfunctions, restoring the original unconditional behavior."
}
],
"id": "CVE-2026-68296",
"lastModified": "2026-08-17T05:18:32.323",
"metrics": {},
"published": "2026-08-10T13:20:19.053",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"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"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-08-31T11:21:20+00:00",
"cve": "CVE-2026-68296",
"id": "CVE-2026-68296",
"initial_release_date": "2026-08-10T00:00:00+00:00",
"product_status:known_affected": "183",
"product_status:known_not_affected": "94",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: net: gre: fix lltx regression for GRE tunnels with SEQ/CSUM",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-68296.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "moderate",
"current_release_date": "2026-09-22T16:44:00Z",
"cve": "CVE-2026-68296",
"id": "CVE-2026-68296",
"initial_release_date": "2026-08-14T17:14:31Z",
"product_status:first_fixed": "60",
"product_status:known_affected": "29",
"product_status:known_not_affected": "345",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-68296",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-68296.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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