GHSA-CCMH-PFGG-525G
Vulnerability from github – Published: 2025-05-20 18:30 – Updated: 2025-12-17 21:30In the Linux kernel, the following vulnerability has been resolved:
sch_htb: make htb_deactivate() idempotent
Alan reported a NULL pointer dereference in htb_next_rb_node() after we made htb_qlen_notify() idempotent.
It turns out in the following case it introduced some regression:
htb_dequeue_tree(): |-> fq_codel_dequeue() |-> qdisc_tree_reduce_backlog() |-> htb_qlen_notify() |-> htb_deactivate() |-> htb_next_rb_node() |-> htb_deactivate()
For htb_next_rb_node(), after calling the 1st htb_deactivate(), the clprio[prio]->ptr could be already set to NULL, which means htb_next_rb_node() is vulnerable here.
For htb_deactivate(), although we checked qlen before calling it, in case of qlen==0 after qdisc_tree_reduce_backlog(), we may call it again which triggers the warning inside.
To fix the issues here, we need to:
1) Make htb_deactivate() idempotent, that is, simply return if we already call it before. 2) Make htb_next_rb_node() safe against ptr==NULL.
Many thanks to Alan for testing and for the reproducer.
{
"affected": [],
"aliases": [
"CVE-2025-37953"
],
"database_specific": {
"cwe_ids": [
"CWE-476"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-05-20T16:15:33Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsch_htb: make htb_deactivate() idempotent\n\nAlan reported a NULL pointer dereference in htb_next_rb_node()\nafter we made htb_qlen_notify() idempotent.\n\nIt turns out in the following case it introduced some regression:\n\nhtb_dequeue_tree():\n |-\u003e fq_codel_dequeue()\n |-\u003e qdisc_tree_reduce_backlog()\n |-\u003e htb_qlen_notify()\n |-\u003e htb_deactivate()\n |-\u003e htb_next_rb_node()\n |-\u003e htb_deactivate()\n\nFor htb_next_rb_node(), after calling the 1st htb_deactivate(), the\nclprio[prio]-\u003eptr could be already set to NULL, which means\nhtb_next_rb_node() is vulnerable here.\n\nFor htb_deactivate(), although we checked qlen before calling it, in\ncase of qlen==0 after qdisc_tree_reduce_backlog(), we may call it again\nwhich triggers the warning inside.\n\nTo fix the issues here, we need to:\n\n1) Make htb_deactivate() idempotent, that is, simply return if we\n already call it before.\n2) Make htb_next_rb_node() safe against ptr==NULL.\n\nMany thanks to Alan for testing and for the reproducer.",
"id": "GHSA-ccmh-pfgg-525g",
"modified": "2025-12-17T21:30:29Z",
"published": "2025-05-20T18:30:56Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-37953"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/31ff70ad39485698cf779f2078132d80b57f6c07"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3769478610135e82b262640252d90f6efb05be71"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/98cd7ed92753090a714f0802d4434314526fe61d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/99ff8a20fd61315bf9ae627440a5ff07d22ee153"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a9945f7cf1709adc5d2d31cb6cfc85627ce299a8"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c2d25fddd867ce20a266806634eeeb5c30cb520c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c4792b9e38d2f61b07eac72f10909fa76130314b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c928dd4f6bf0c25c72b11824a1e9ac9bd37296a0"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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.