GHSA-9CFQ-2RJH-R5VR
Vulnerability from github – Published: 2026-09-04 18:31 – Updated: 2026-09-04 18:31In the Linux kernel, the following vulnerability has been resolved:
vxlan: keep the last remote linked during FDB flush
A non-nexthop FDB entry is expected to have at least one remote while it remains reachable through the FDB hash table. A filtered bulk flush violates this invariant when every remote matches: It unlinks the last remote in vxlan_fdb_dst_destroy() and only afterwards tells vxlan_flush() to destroy the parent FDB entry.
An RCU reader can find the parent during this interval. first_remote_rcu() then applies list_entry_rcu() to the empty list head, producing an invalid remote pointer that the receive learning path can read from and write to.
When a matching remote is the sole remaining remote, leave it linked and ask the caller to destroy the entire FDB entry. vxlan_fdb_destroy() keeps the remote attached while sending the deletion notification and removing the parent from the lookup structures.
{
"affected": [],
"aliases": [
"CVE-2026-80838"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-04T16:18:12Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nvxlan: keep the last remote linked during FDB flush\n\nA non-nexthop FDB entry is expected to have at least one remote while it\nremains reachable through the FDB hash table. A filtered bulk flush\nviolates this invariant when every remote matches: It unlinks the last\nremote in vxlan_fdb_dst_destroy() and only afterwards tells vxlan_flush()\nto destroy the parent FDB entry.\n\nAn RCU reader can find the parent during this interval.\nfirst_remote_rcu() then applies list_entry_rcu() to the empty list head,\nproducing an invalid remote pointer that the receive learning path can\nread from and write to.\n\nWhen a matching remote is the sole remaining remote, leave it linked and\nask the caller to destroy the entire FDB entry. vxlan_fdb_destroy() keeps\nthe remote attached while sending the deletion notification and removing\nthe parent from the lookup structures.",
"id": "GHSA-9cfq-2rjh-r5vr",
"modified": "2026-09-04T18:31:28Z",
"published": "2026-09-04T18:31:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80838"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2a7c2f00843225d5f037676bca649321f3d024c7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4bbc76ee1b21d3bd045d6d819b2bacd30a6372ab"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8ba68fd6cdd1e3c92b92f25c7e48bf7bd51a183c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a8820c8a7718327e96849782033e7c85a0f6bcfe"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d5d4a7b538b52db63927773a8905fcd9f78a42e2"
}
],
"schema_version": "1.4.0",
"severity": []
}
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.
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.