FKIE_CVE-2026-63992
Vulnerability from fkie_nvd - Published: 2026-07-19 16:17 - Updated: 2026-07-30 14:51
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved:
tunnels: do not assume transport header in iptunnel_pmtud_check_icmp()
In some cases, iptunnel_pmtud_check_icmp() can be called while
skb transport header is not set.
This triggers an out-of-bound access, because
(typeof(skb->transport_header))~0U is 65535.
Access the icmp header based on IPv4 network header,
after making sure icmp->type is present in skb linear part.
Note that iptunnel_pmtud_check_icmpv6()) is fine.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/ipv4/ip_tunnel_core.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "5a92cb45e34749865d03daf8d3500f77b5f6644c",
"status": "affected",
"version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
"versionType": "git"
},
{
"lessThan": "c7b7ec3e69e673c0d6b57f74d21da50c485c598e",
"status": "affected",
"version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
"versionType": "git"
},
{
"lessThan": "7f4f7efe7f30edd29c4988de01728bf2398217e4",
"status": "affected",
"version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
"versionType": "git"
},
{
"lessThan": "e917d0c69f01af2bb4fbea2b66d560a53b3ac7ec",
"status": "affected",
"version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
"versionType": "git"
},
{
"lessThan": "a096b6e34f602950af9a2b0856cd93a5f4c276d7",
"status": "affected",
"version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
"versionType": "git"
},
{
"lessThan": "43368636c663cff6e59dde93cf4b8e43ac28eb93",
"status": "affected",
"version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
"versionType": "git"
},
{
"lessThan": "cb549df9ce4ee15c9d5b19ddab12cf2128e4313c",
"status": "affected",
"version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
"versionType": "git"
},
{
"lessThan": "509323077ef79a26ba0c60bb556e45c12c398b2d",
"status": "affected",
"version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/ipv4/ip_tunnel_core.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.9"
},
{
"lessThan": "5.9",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.259",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.210",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.176",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.143",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.93",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.35",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.0.*",
"status": "unaffected",
"version": "7.0.12",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.1",
"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\ntunnels: do not assume transport header in iptunnel_pmtud_check_icmp()\n\nIn some cases, iptunnel_pmtud_check_icmp() can be called while\nskb transport header is not set.\n\nThis triggers an out-of-bound access, because\n(typeof(skb-\u003etransport_header))~0U is 65535.\n\nAccess the icmp header based on IPv4 network header,\nafter making sure icmp-\u003etype is present in skb linear part.\n\nNote that iptunnel_pmtud_check_icmpv6()) is fine."
}
],
"id": "CVE-2026-63992",
"lastModified": "2026-07-30T14:51:11.223",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 9.1,
"baseSeverity": "CRITICAL",
"confidentialityImpact": "HIGH",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
"version": "3.1"
},
"exploitabilityScore": 3.9,
"impactScore": 5.2,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-07-19T16:17:38.700",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/43368636c663cff6e59dde93cf4b8e43ac28eb93"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/509323077ef79a26ba0c60bb556e45c12c398b2d"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/5a92cb45e34749865d03daf8d3500f77b5f6644c"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/7f4f7efe7f30edd29c4988de01728bf2398217e4"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/a096b6e34f602950af9a2b0856cd93a5f4c276d7"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/c7b7ec3e69e673c0d6b57f74d21da50c485c598e"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/cb549df9ce4ee15c9d5b19ddab12cf2128e4313c"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/e917d0c69f01af2bb4fbea2b66d560a53b3ac7ec"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Awaiting Analysis"
}
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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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