CVE-2026-31675 (GCVE-0-2026-31675)
Vulnerability from cvelistv5 – Published: 2026-04-25 08:46 – Updated: 2026-08-05 12:24
VLAI
EPSS
VEX
Title
net/sched: sch_netem: fix out-of-bounds access in packet corruption
Summary
In the Linux kernel, the following vulnerability has been resolved:
net/sched: sch_netem: fix out-of-bounds access in packet corruption
In netem_enqueue(), the packet corruption logic uses
get_random_u32_below(skb_headlen(skb)) to select an index for
modifying skb->data. When an AF_PACKET TX_RING sends fully non-linear
packets over an IPIP tunnel, skb_headlen(skb) evaluates to 0.
Passing 0 to get_random_u32_below() takes the variable-ceil slow path
which returns an unconstrained 32-bit random integer. Using this
unconstrained value as an offset into skb->data results in an
out-of-bounds memory access.
Fix this by verifying skb_headlen(skb) is non-zero before attempting
to corrupt the linear data area. Fully non-linear packets will silently
bypass the corruption logic.
Severity
7.8 (High)
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
c865e5d99e25a171e8262fc0f7ba608568633c64 , < a14b56863348686dd0387eea8ce66b85cf455908
(git)
Affected: c865e5d99e25a171e8262fc0f7ba608568633c64 , < 13a66ca1e235d4bcd53d12d4c68490cad7f8e46f (git) Affected: c865e5d99e25a171e8262fc0f7ba608568633c64 , < 3a2999704ac36cfb4041fed3652d26a3373e8d12 (git) Affected: c865e5d99e25a171e8262fc0f7ba608568633c64 , < 4fd258e281fa8bc15e9ce2c7691941537e9258ad (git) Affected: c865e5d99e25a171e8262fc0f7ba608568633c64 , < d64cb81dcbd54927515a7f65e5e24affdc73c14b (git) |
guessed | |
| Linux | Linux |
Affected:
2.6.16
Unaffected: 0 , < 2.6.16 (semver) Unaffected: 6.6.134 , ≤ 6.6.* (semver) Unaffected: 6.12.81 , ≤ 6.12.* (semver) Unaffected: 6.18.22 , ≤ 6.18.* (semver) Unaffected: 6.19.12 , ≤ 6.19.* (semver) Unaffected: 7.0 , ≤ * (original_commit_for_fix) |
guessed |
{
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_netem: fix out-of-bounds access in packet corruption\n\nIn netem_enqueue(), the packet corruption logic uses\nget_random_u32_below(skb_headlen(skb)) to select an index for\nmodifying skb-\u003edata. When an AF_PACKET TX_RING sends fully non-linear\npackets over an IPIP tunnel, skb_headlen(skb) evaluates to 0.\n\nPassing 0 to get_random_u32_below() takes the variable-ceil slow path\nwhich returns an unconstrained 32-bit random integer. Using this\nunconstrained value as an offset into skb-\u003edata results in an\nout-of-bounds memory access.\n\nFix this by verifying skb_headlen(skb) is non-zero before attempting\nto corrupt the linear data area. Fully non-linear packets will silently\nbypass the corruption logic."
}
],
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"version": "3.1"
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"value": "AV:L - Triggering requires local kernel interfaces: configuring a `netem` qdisc via rtnetlink and sending crafted AF_PACKET TX_RING traffic over an IPIP tunnel. This is not directly reachable by unauthenticated remote packets.\nAC:L - The attacker controls the qdisc corruption setting and the fully non-linear skb construction path, with no race or victim state required. The corrupt probability can be configured to make the vulnerable access occur reliably.\nPR:L - The path requires `CAP_NET_ADMIN` for traffic control and `CAP_NET_RAW` for AF_PACKET, but both are obtainable inside attacker-created user/network namespaces on systems permitting unprivileged user namespaces. Therefore this is low privilege rather than real init-namespace root.\nUI:N - No victim action is needed once the local attacker can issue the relevant netlink and socket syscalls. The attacker triggers the enqueue path directly.\nS:U - The corruption occurs within the kernel networking/qdisc subsystem and impacts the same kernel security authority. It is a standard local kernel compromise scenario, not a VM or hardware boundary escape.\nC:H - The bug is an out-of-bounds kernel memory read-modify-write through an unconstrained offset from `skb-\u003edata`. As kernel memory corruption, successful exploitation can plausibly yield arbitrary kernel memory disclosure.\nI:H - The vulnerable operation flips a bit at an out-of-bounds kernel address, giving a kernel memory corruption primitive. Under the required overestimation rule, this supports potential control-flow hijack or privilege escalation.\nA:H - The unconstrained out-of-bounds kernel access can fault or corrupt critical kernel memory. A local attacker can repeatedly trigger it, making kernel oops/panic or system instability high impact."
}
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"providerMetadata": {
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},
{
"url": "https://git.kernel.org/stable/c/d64cb81dcbd54927515a7f65e5e24affdc73c14b"
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"datePublished": "2026-04-25T08:46:51.184Z",
"dateReserved": "2026-03-09T15:48:24.130Z",
"dateUpdated": "2026-08-05T12:24:22.485Z",
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"date": "2026-09-15",
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Using this\\nunconstrained value as an offset into skb-\u003edata results in an\\nout-of-bounds memory access.\\n\\nFix this by verifying skb_headlen(skb) is non-zero before attempting\\nto corrupt the linear data area. Fully non-linear packets will silently\\nbypass the corruption 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"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-07-02T17:15:09+00:00",
"cve": "CVE-2026-31675",
"id": "CVE-2026-31675",
"initial_release_date": "2026-04-25T00:00:00+00:00",
"product_status:known_affected": "260",
"product_status:known_not_affected": "14",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: net/sched: sch_netem: fix out-of-bounds access in packet corruption",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-31675.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "moderate",
"current_release_date": "2026-09-11T01:29:30Z",
"cve": "CVE-2026-31675",
"id": "CVE-2026-31675",
"initial_release_date": "2026-04-26T01:52:47Z",
"product_status:first_fixed": "2",
"product_status:known_affected": "665",
"product_status:recommended": "317",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-31675",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-31675.json",
"version": "23"
}
}
}
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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.
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.
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