CVE-2025-21791 (GCVE-0-2025-21791)
Vulnerability from cvelistv5 – Published: 2025-02-27 02:18 – Updated: 2026-08-05 11:54
VLAI
EPSS
VEX
Title
vrf: use RCU protection in l3mdev_l3_out()
Summary
In the Linux kernel, the following vulnerability has been resolved:
vrf: use RCU protection in l3mdev_l3_out()
l3mdev_l3_out() can be called without RCU being held:
raw_sendmsg()
ip_push_pending_frames()
ip_send_skb()
ip_local_out()
__ip_local_out()
l3mdev_ip_out()
Add rcu_read_lock() / rcu_read_unlock() pair to avoid
a potential UAF.
Severity
7.8 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2025-02-27 17:57 UTC
CWE
- CWE-416 - Use After Free
Assigner
References
10 references
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
a8e3e1a9f02094145580ea7920c6a1d9aabd5539 , < 6ccaa5797f5362a2aad6baa6ddaf4715ac2dd51e
(git)
Affected: a8e3e1a9f02094145580ea7920c6a1d9aabd5539 , < 20a3489b396764cc9376e32a9172bee26a89dc3b (git) Affected: a8e3e1a9f02094145580ea7920c6a1d9aabd5539 , < 5bb4228c32261d06e4fbece37ec3828bcc005b6b (git) Affected: a8e3e1a9f02094145580ea7920c6a1d9aabd5539 , < c7574740be8ce68a57d0aece24987b9be2114c3c (git) Affected: a8e3e1a9f02094145580ea7920c6a1d9aabd5539 , < c40cb5c03e37552d6eff963187109e2c3f78ef6f (git) Affected: a8e3e1a9f02094145580ea7920c6a1d9aabd5539 , < 022cac1c693add610ae76ede03adf4d9d5a2cf21 (git) Affected: a8e3e1a9f02094145580ea7920c6a1d9aabd5539 , < 7b81425b517accefd46bee854d94954f5c57e019 (git) Affected: a8e3e1a9f02094145580ea7920c6a1d9aabd5539 , < 6d0ce46a93135d96b7fa075a94a88fe0da8e8773 (git) |
guessed | |
| Linux | Linux |
Affected:
4.9
Unaffected: 0 , < 4.9 (semver) Unaffected: 5.4.291 , ≤ 5.4.* (semver) Unaffected: 5.10.235 , ≤ 5.10.* (semver) Unaffected: 5.15.179 , ≤ 5.15.* (semver) Unaffected: 6.1.129 , ≤ 6.1.* (semver) Unaffected: 6.6.79 , ≤ 6.6.* (semver) Unaffected: 6.12.16 , ≤ 6.12.* (semver) Unaffected: 6.13.4 , ≤ 6.13.* (semver) Unaffected: 6.14 , ≤ * (original_commit_for_fix) |
guessed |
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},
{
"source": "af854a3a-2127-422b-91ae-364da2661108",
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},
{
"source": "af854a3a-2127-422b-91ae-364da2661108",
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}
],
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},
{
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}
],
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"type": "Secondary"
}
]
}
},
"redhat_vex": {
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"current_release_date": "2026-08-19T19:21:52+00:00",
"cve": "CVE-2025-21791",
"id": "CVE-2025-21791",
"initial_release_date": "2025-02-27T00:00:00+00:00",
"product_status:fixed": "917",
"product_status:known_affected": "112",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: vrf: use RCU protection in l3mdev_l3_out()",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-21791.json",
"version": "3"
},
"vulnrichment": {
"containers": {
"adp": [
{
"providerMetadata": {
"dateUpdated": "2025-11-03T20:59:34.647Z",
"orgId": "af854a3a-2127-422b-91ae-364da2661108",
"shortName": "CVE"
},
"references": [
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},
{
"url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html"
}
],
"title": "CVE Program Container"
},
{
"metrics": [
{
"cvssV3_1": {
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"version": "3.1"
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},
{
"other": {
"content": {
"id": "CVE-2025-21791",
"options": [
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},
{
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},
{
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],
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"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"problemTypes": [
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"descriptions": [
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"lang": "en",
"type": "CWE"
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]
}
],
"providerMetadata": {
"dateUpdated": "2025-02-27T17:57:17.808Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
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"cna": {
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},
{
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"status": "unaffected",
"version": "0",
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},
{
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"status": "unaffected",
"version": "5.4.291",
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},
{
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},
{
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}
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"value": "AV:L - Both halves of the race are driven from the local system \u2014 a `sendmsg()` on a local socket for the read side, and RTNL link operations (VRF delete/unenslave) for the free side. A remote peer cannot induce the VRF teardown that arms the use-after-free.\nAC:L - The attacker controls both sides of the race and can loop them indefinitely: one thread sends UDP/raw packets out a VRF-enslaved device while another repeatedly unenslaves/deletes the VRF master, with preemption pressure raised at will. `do_vrf_del_slave()` widens the window further by unlinking the adjacency before clearing `IFF_L3MDEV_SLAVE`.\nPR:L - The transmit side needs no privileges at all (ordinary UDP sendmsg), and the VRF create/enslave/delete side needs only CAP_NET_ADMIN within a network namespace, which an unprivileged user obtains via `unshare -Urn`.\nUI:N - The attacker\u0027s own threads perform every step \u2014 socket sends and netlink link operations \u2014 with no victim action required.\nS:U - The use-after-free and its consequences are confined to the kernel\u0027s own security authority; no VM, IOMMU, or other trust boundary is crossed.\nC:H - The freed `netdev_adjacent` sits in a general kmalloc cache and is readily groomed, letting the attacker supply `upper-\u003edev`, after which `master-\u003el3mdev_ops` and `-\u003el3mdev_l3_out` are read from an attacker-chosen address \u2014 an arbitrary kernel read primitive.\nI:H - The same reclaimed object yields an indirect call through an attacker-controlled function pointer with `master` as the first argument, giving control-flow hijack and thus arbitrary kernel-state modification.\nA:H - Even unweaponized, dereferencing a stale adjacency entry and calling through garbage function pointers reliably oopses or panics the kernel, and the attacker can retrigger it at will."
}
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}
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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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