CVE-2026-74705 (GCVE-0-2026-74705)
Vulnerability from cvelistv5 – Published: 2026-08-22 15:33 – Updated: 2026-10-16 19:16
VLAI
EPSS
VEX
Title
udp: fix potential use-after-free in tunnel segmentation
Summary
In the Linux kernel, the following vulnerability has been resolved:
udp: fix potential use-after-free in tunnel segmentation
__skb_udp_tunnel_segment() gets the UDP header before ensuring the
tunnel header is in the skb head. If the pull reallocates skb->head,
the saved UDP header pointer is no longer valid.
Get the UDP header after the pull to avoid a potential use-after-free.
Severity
10 (Critical)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-16 19:15 UTC
Assigner
References
8 references
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
dbef491ebe7f3a4fb1b9111878b86a426fd540b7 , < 6a733a38b983d8c2e222f13968209010cf44de87
(git)
Affected: dbef491ebe7f3a4fb1b9111878b86a426fd540b7 , < 19d89b13a43640b2da2f277ee462d919d988cb6f (git) Affected: dbef491ebe7f3a4fb1b9111878b86a426fd540b7 , < b3df61bb745eb5201eac22679a2839d4ccbf3442 (git) Affected: dbef491ebe7f3a4fb1b9111878b86a426fd540b7 , < 1ae134c012e10384cdac420b5cc6e0615cde0b55 (git) Affected: dbef491ebe7f3a4fb1b9111878b86a426fd540b7 , < 5161e67c561c4f28a5d9335a6e859b02511de92b (git) Affected: dbef491ebe7f3a4fb1b9111878b86a426fd540b7 , < 64d322c288577793eedd352b96ef75234ed380fe (git) Affected: dbef491ebe7f3a4fb1b9111878b86a426fd540b7 , < 588d4a6795d99d080f74ef0b5f391ea8c453ae5d (git) Affected: dbef491ebe7f3a4fb1b9111878b86a426fd540b7 , < d0f86fb36eb260abd10007b62c9dcc1028e03e61 (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: 6.1.183 , ≤ 6.1.* (semver) Unaffected: 6.6.152 , ≤ 6.6.* (semver) Unaffected: 6.12.104 , ≤ 6.12.* (semver) Unaffected: 6.18.45 , ≤ 6.18.* (semver) Unaffected: 7.1.9 , ≤ 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\nudp: fix potential use-after-free in tunnel segmentation\n\n__skb_udp_tunnel_segment() gets the UDP header before ensuring the\ntunnel header is in the skb head. If the pull reallocates skb-\u003ehead,\nthe saved UDP header pointer is no longer valid.\n\nGet the UDP header after the pull to avoid a potential use-after-free."
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"cve": "CVE-2026-74705",
"id": "CVE-2026-74705",
"initial_release_date": "2026-08-22T00:00:00+00:00",
"product_status:fixed": "2096",
"product_status:known_affected": "22",
"product_status:known_not_affected": "14",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: udp: fix potential use-after-free in tunnel segmentation",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74705.json",
"version": "3"
},
"vulnrichment": {
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-74705",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-10-16T19:15:04.524382Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-10-16T19:15:05.632Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/ipv4/udp_offload.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "6a733a38b983d8c2e222f13968209010cf44de87",
"status": "affected",
"version": "dbef491ebe7f3a4fb1b9111878b86a426fd540b7",
"versionType": "git"
},
{
"lessThan": "19d89b13a43640b2da2f277ee462d919d988cb6f",
"status": "affected",
"version": "dbef491ebe7f3a4fb1b9111878b86a426fd540b7",
"versionType": "git"
},
{
"lessThan": "b3df61bb745eb5201eac22679a2839d4ccbf3442",
"status": "affected",
"version": "dbef491ebe7f3a4fb1b9111878b86a426fd540b7",
"versionType": "git"
},
{
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"status": "affected",
"version": "dbef491ebe7f3a4fb1b9111878b86a426fd540b7",
"versionType": "git"
},
{
"lessThan": "5161e67c561c4f28a5d9335a6e859b02511de92b",
"status": "affected",
"version": "dbef491ebe7f3a4fb1b9111878b86a426fd540b7",
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{
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"status": "affected",
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},
{
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"status": "affected",
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"versionType": "git"
},
{
"lessThan": "d0f86fb36eb260abd10007b62c9dcc1028e03e61",
"status": "affected",
"version": "dbef491ebe7f3a4fb1b9111878b86a426fd540b7",
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]
},
{
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"product": "Linux",
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],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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"status": "affected",
"version": "4.6"
},
{
"lessThan": "4.6",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.265",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.216",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.183",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.152",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.104",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.45",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.9",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.10.265",
"versionStartIncluding": "4.6",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.15.216",
"versionStartIncluding": "4.6",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.183",
"versionStartIncluding": "4.6",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.104",
"versionStartIncluding": "4.6",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.45",
"versionStartIncluding": "4.6",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.9",
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},
{
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"versionEndExcluding": "7.2",
"versionStartIncluding": "4.6",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nudp: fix potential use-after-free in tunnel segmentation\n\n__skb_udp_tunnel_segment() gets the UDP header before ensuring the\ntunnel header is in the skb head. If the pull reallocates skb-\u003ehead,\nthe saved UDP header pointer is no longer valid.\n\nGet the UDP header after the pull to avoid a potential use-after-free."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 10,
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - Remote peers reach __skb_udp_tunnel_segment on egress when GRO-coalesced VXLAN/Geneve/FOU GSO superpackets are forwarded or re-encapsulated through dev_queue_xmit, and malicious virtio-net/cloud tenants can inject VIRTIO_NET_HDR_GSO_UDP_TUNNEL frames the host later segments on physical or overlay NICs.\nAC:L - Triggering is deterministic once a GSO UDP-tunnel skb has tunnel headers beyond skb_headlen so pskb_may_pull reallocates skb-\u003ehead; attackers control that layout via fragmented or GRO-built outer/encap headers and can repeat crafted sends until segmentation dereferences the stale UDP pointer.\nPR:N - No host authentication or credentials are required to send UDP tunnel traffic to listening overlay ports on cloud/DC nodes, and co-resident virtio-net guests or tenant VMs can emit GSO UDP-tunnel frames into the host datapath without CAP_NET_ADMIN on the victim host.\nUI:N - Exploitation needs only crafted encapsulated GSO traffic into an already-running overlay, bridge, IPVS, OVS, or virtio forwarding path; no victim file open, mount, link click, or other interactive action beyond normal network or VM I/O.\nS:C - In cloud/Kubernetes and virtio-net multitenant deployments, remote or guest/tenant senders can corrupt hypervisor kernel heap during host-side UDP-tunnel GSO segmentation on egress, crossing the VM/container-to-host security boundary rather than staying within the attacker\u0027s own namespace.\nC:H - After pskb_may_pull reallocates skb-\u003ehead, the pre-pull udp_hdr pointer is stale yet uh-\u003elen and uh-\u003echeck are read for checksum adjustment, yielding a classic heap use-after-free read primitive that can disclose kernel memory and support further exploitation.\nI:H - UAF on the UDP header allows attacker-influenced heap reuse and corruption of header fields and checksum state during tunnel GSO segmentation, providing a write/control primitive suitable for kernel code execution rather than a benign checksum miscalculation.\nA:H - Dereferencing the freed UDP header during GSO segmentation can immediately oops or panic the kernel, and repeated exploitation attempts against this UAF commonly crash or hang the host even when full control is not achieved."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-25T05:41:48.767Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
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"references": [
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"url": "https://git.kernel.org/stable/c/6a733a38b983d8c2e222f13968209010cf44de87"
},
{
"url": "https://git.kernel.org/stable/c/19d89b13a43640b2da2f277ee462d919d988cb6f"
},
{
"url": "https://git.kernel.org/stable/c/b3df61bb745eb5201eac22679a2839d4ccbf3442"
},
{
"url": "https://git.kernel.org/stable/c/1ae134c012e10384cdac420b5cc6e0615cde0b55"
},
{
"url": "https://git.kernel.org/stable/c/5161e67c561c4f28a5d9335a6e859b02511de92b"
},
{
"url": "https://git.kernel.org/stable/c/64d322c288577793eedd352b96ef75234ed380fe"
},
{
"url": "https://git.kernel.org/stable/c/588d4a6795d99d080f74ef0b5f391ea8c453ae5d"
},
{
"url": "https://git.kernel.org/stable/c/d0f86fb36eb260abd10007b62c9dcc1028e03e61"
}
],
"title": "udp: fix potential use-after-free in tunnel segmentation",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74705",
"datePublished": "2026-08-22T15:33:04.110Z",
"dateReserved": "2026-08-15T05:44:03.927Z",
"dateUpdated": "2026-10-16T19:16:10.609Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
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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
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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.