CVE-2026-31649 (GCVE-0-2026-31649)
Vulnerability from cvelistv5 – Published: 2026-04-24 14:45 – Updated: 2026-10-19 18:56
VLAI
EPSS
VEX
Title
net: stmmac: fix integer underflow in chain mode
Summary
In the Linux kernel, the following vulnerability has been resolved:
net: stmmac: fix integer underflow in chain mode
The jumbo_frm() chain-mode implementation unconditionally computes
len = nopaged_len - bmax;
where nopaged_len = skb_headlen(skb) (linear bytes only) and bmax is
BUF_SIZE_8KiB or BUF_SIZE_2KiB. However, the caller stmmac_xmit()
decides to invoke jumbo_frm() based on skb->len (total length including
page fragments):
is_jumbo = stmmac_is_jumbo_frm(priv, skb->len, enh_desc);
When a packet has a small linear portion (nopaged_len <= bmax) but a
large total length due to page fragments (skb->len > bmax), the
subtraction wraps as an unsigned integer, producing a huge len value
(~0xFFFFxxxx). This causes the while (len != 0) loop to execute
hundreds of thousands of iterations, passing skb->data + bmax * i
pointers far beyond the skb buffer to dma_map_single(). On IOMMU-less
SoCs (the typical deployment for stmmac), this maps arbitrary kernel
memory to the DMA engine, constituting a kernel memory disclosure and
potential memory corruption from hardware.
Fix this by introducing a buf_len local variable clamped to
min(nopaged_len, bmax). Computing len = nopaged_len - buf_len is then
always safe: it is zero when the linear portion fits within a single
descriptor, causing the while (len != 0) loop to be skipped naturally,
and the fragment loop in stmmac_xmit() handles page fragments afterward.
Severity
9.8 (Critical)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-16 15:11 UTC
CWE
- CWE-190 - Integer Overflow or Wraparound
Assigner
References
11 references
Impacted products
11 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
286a837217204b1ef105e3a554d0757e4fdfaac1 , < 513e06735f5be575b409d195822195348b164e48
(git)
Affected: 286a837217204b1ef105e3a554d0757e4fdfaac1 , < 275bdf762e82082f064e60a92448fa2ac43cf95b (git) Affected: 286a837217204b1ef105e3a554d0757e4fdfaac1 , < a2b68a9a476b9544ff31f1fbcd5d80867a8a5e2f (git) Affected: 286a837217204b1ef105e3a554d0757e4fdfaac1 , < b7b8012193fd98236d7ae05d4b553f010a77b2ef (git) Affected: 286a837217204b1ef105e3a554d0757e4fdfaac1 , < 2c91b39912278d0878f9ba60ba04d2518b18a08d (git) Affected: 286a837217204b1ef105e3a554d0757e4fdfaac1 , < 6fca757c20396dc2e604dcc61922264e9e3dc803 (git) Affected: 286a837217204b1ef105e3a554d0757e4fdfaac1 , < 10d12b9240ebf96c785f0e2e4228318cd5f3a3eb (git) Affected: 286a837217204b1ef105e3a554d0757e4fdfaac1 , < 51f4e090b9f87b40c21b6daadb5c06e6c0a07b67 (git) |
guessed | |
| Linux | Linux |
Affected:
3.2
Unaffected: 0 , < 3.2 (semver) Unaffected: 5.10.253 , ≤ 5.10.* (semver) Unaffected: 5.15.203 , ≤ 5.15.* (semver) Unaffected: 6.1.169 , ≤ 6.1.* (semver) Unaffected: 6.6.135 , ≤ 6.6.* (semver) Unaffected: 6.12.82 , ≤ 6.12.* (semver) Unaffected: 6.18.23 , ≤ 6.18.* (semver) Unaffected: 6.19.13 , ≤ 6.19.* (semver) Unaffected: 7.0 , ≤ * (original_commit_for_fix) |
guessed | |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP |
Affected:
V3.1.6 , < *
(custom)
|
guessed | |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP |
Affected:
V3.1.5 , < *
(custom)
|
guessed | |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP |
Affected:
V3.1.7 , < *
(custom)
|
guessed | |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP |
Affected:
V3.1.6 , < *
(custom)
|
guessed | |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP |
Affected:
V3.1.5 , < *
(custom)
|
guessed | |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP |
Affected:
V3.1.7 , < *
(custom)
|
guessed | |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP |
Affected:
V3.1.6 , < *
(custom)
|
guessed | |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP |
Affected:
V3.1.5 , < *
(custom)
|
guessed | |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP |
Affected:
V3.1.7 , < *
(custom)
|
guessed |
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: stmmac: fix integer underflow in chain mode\n\nThe jumbo_frm() chain-mode implementation unconditionally computes\n\n len = nopaged_len - bmax;\n\nwhere nopaged_len = skb_headlen(skb) (linear bytes only) and bmax is\nBUF_SIZE_8KiB or BUF_SIZE_2KiB. However, the caller stmmac_xmit()\ndecides to invoke jumbo_frm() based on skb-\u003elen (total length including\npage fragments):\n\n is_jumbo = stmmac_is_jumbo_frm(priv, skb-\u003elen, enh_desc);\n\nWhen a packet has a small linear portion (nopaged_len \u003c= bmax) but a\nlarge total length due to page fragments (skb-\u003elen \u003e bmax), the\nsubtraction wraps as an unsigned integer, producing a huge len value\n(~0xFFFFxxxx). This causes the while (len != 0) loop to execute\nhundreds of thousands of iterations, passing skb-\u003edata + bmax * i\npointers far beyond the skb buffer to dma_map_single(). On IOMMU-less\nSoCs (the typical deployment for stmmac), this maps arbitrary kernel\nmemory to the DMA engine, constituting a kernel memory disclosure and\npotential memory corruption from hardware.\n\nFix this by introducing a buf_len local variable clamped to\nmin(nopaged_len, bmax). Computing len = nopaged_len - buf_len is then\nalways safe: it is zero when the linear portion fits within a single\ndescriptor, causing the while (len != 0) loop to be skipped naturally,\nand the fragment loop in stmmac_xmit() handles page fragments afterward."
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}
]
},
{
"defaultStatus": "unknown",
"product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP",
"vendor": "Siemens",
"versions": [
{
"lessThan": "*",
"status": "affected",
"version": "V3.1.7",
"versionType": "custom"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-10-15T01:17:28.732Z",
"orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
"shortName": "siemens-SADP"
},
"references": [
{
"url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html"
},
{
"url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
},
{
"url": "https://cert-portal.siemens.com/productcert/html/ssa-457936.html"
}
],
"x_adpType": "supplier"
},
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-31649",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-10-16T15:11:32.382744Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-190",
"description": "CWE-190 Integer Overflow or Wraparound",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-10-16T15:11:33.056Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"drivers/net/ethernet/stmicro/stmmac/chain_mode.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "513e06735f5be575b409d195822195348b164e48",
"status": "affected",
"version": "286a837217204b1ef105e3a554d0757e4fdfaac1",
"versionType": "git"
},
{
"lessThan": "275bdf762e82082f064e60a92448fa2ac43cf95b",
"status": "affected",
"version": "286a837217204b1ef105e3a554d0757e4fdfaac1",
"versionType": "git"
},
{
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"status": "affected",
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"versionType": "git"
},
{
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"status": "affected",
"version": "286a837217204b1ef105e3a554d0757e4fdfaac1",
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{
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{
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{
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{
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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": "3.2"
},
{
"lessThan": "3.2",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "5.10.253",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "5.15.203",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "6.1.169",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.135",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.82",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.23",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.19.*",
"status": "unaffected",
"version": "6.19.13",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "7.0",
"versionType": "original_commit_for_fix"
}
]
}
],
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"nodes": [
{
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"versionStartIncluding": "3.2",
"vulnerable": true
},
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},
{
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"vulnerable": true
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{
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"versionEndExcluding": "6.18.23",
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},
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},
{
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"versionEndExcluding": "7.0",
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"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: stmmac: fix integer underflow in chain mode\n\nThe jumbo_frm() chain-mode implementation unconditionally computes\n\n len = nopaged_len - bmax;\n\nwhere nopaged_len = skb_headlen(skb) (linear bytes only) and bmax is\nBUF_SIZE_8KiB or BUF_SIZE_2KiB. However, the caller stmmac_xmit()\ndecides to invoke jumbo_frm() based on skb-\u003elen (total length including\npage fragments):\n\n is_jumbo = stmmac_is_jumbo_frm(priv, skb-\u003elen, enh_desc);\n\nWhen a packet has a small linear portion (nopaged_len \u003c= bmax) but a\nlarge total length due to page fragments (skb-\u003elen \u003e bmax), the\nsubtraction wraps as an unsigned integer, producing a huge len value\n(~0xFFFFxxxx). This causes the while (len != 0) loop to execute\nhundreds of thousands of iterations, passing skb-\u003edata + bmax * i\npointers far beyond the skb buffer to dma_map_single(). On IOMMU-less\nSoCs (the typical deployment for stmmac), this maps arbitrary kernel\nmemory to the DMA engine, constituting a kernel memory disclosure and\npotential memory corruption from hardware.\n\nFix this by introducing a buf_len local variable clamped to\nmin(nopaged_len, bmax). Computing len = nopaged_len - buf_len is then\nalways safe: it is zero when the linear portion fits within a single\ndescriptor, causing the while (len != 0) loop to be skipped naturally,\nand the fragment loop in stmmac_xmit() handles page fragments afterward."
}
],
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"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
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"value": "AV:N - The vulnerable stmmac transmit path can be reached over the network when an unauthenticated peer causes a network-facing service or forwarding/router workload to transmit large non-linear skbs through an affected stmmac interface. This is a plausible deployment for embedded/router/NFS/TLS systems using this Ethernet MAC.\nAC:L - Once the system is using affected chain mode, the trigger is a non-linear packet whose total length exceeds the jumbo threshold while the linear head does not, which common scatter-gather/sendpage paths can produce. There is no race or attacker-uncontrolled timing requirement.\nPR:N - In the highest reasonable scenario, a remote unauthenticated client can trigger large page-backed responses or forwarded traffic through the vulnerable device. No local account or administrative capability is required for that network-triggered path.\nUI:N - No victim user action is needed beyond the system already running the affected driver and network service or forwarding configuration. The attacker can trigger transmission by network interaction.\nS:U - The vulnerability is in the host kernel network driver and impacts the same host kernel security authority. It does not cross a VM, IOMMU, or other separate security scope boundary by itself.\nC:H - The underflow makes the driver DMA-map addresses far beyond the skb buffer, exposing arbitrary kernel memory to the DMA engine and potentially onto the wire. That supports high confidentiality impact.\nI:H - The erroneous descriptor programming gives hardware DMA access to unintended kernel memory ranges and the fix description identifies potential memory corruption from hardware. Under the required tie-breaker, this is scored as high integrity impact.\nA:H - The huge wrapped loop and invalid DMA mappings can exhaust/overwrite TX descriptors, hit DMA/IOMMU faults, hang transmission, or crash the kernel. This is high availability impact."
}
]
}
],
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
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"url": "https://git.kernel.org/stable/c/513e06735f5be575b409d195822195348b164e48"
},
{
"url": "https://git.kernel.org/stable/c/275bdf762e82082f064e60a92448fa2ac43cf95b"
},
{
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},
{
"url": "https://git.kernel.org/stable/c/b7b8012193fd98236d7ae05d4b553f010a77b2ef"
},
{
"url": "https://git.kernel.org/stable/c/2c91b39912278d0878f9ba60ba04d2518b18a08d"
},
{
"url": "https://git.kernel.org/stable/c/6fca757c20396dc2e604dcc61922264e9e3dc803"
},
{
"url": "https://git.kernel.org/stable/c/10d12b9240ebf96c785f0e2e4228318cd5f3a3eb"
},
{
"url": "https://git.kernel.org/stable/c/51f4e090b9f87b40c21b6daadb5c06e6c0a07b67"
}
],
"title": "net: stmmac: fix integer underflow in chain mode",
"x_generator": {
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"cveMetadata": {
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"assignerShortName": "Linux",
"cveId": "CVE-2026-31649",
"datePublished": "2026-04-24T14:45:02.520Z",
"dateReserved": "2026-03-09T15:48:24.128Z",
"dateUpdated": "2026-10-19T18:56:01.547Z",
"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.