GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

GHSA-62JP-JVC3-7HH9

Vulnerability from github – Published: 2026-03-18 18:31 – Updated: 2026-07-14 15:31
VLAI
Details

In the Linux kernel, the following vulnerability has been resolved:

net/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared blocks

As Paolo said earlier [1]:

"Since the blamed commit below, classify can return TC_ACT_CONSUMED while the current skb being held by the defragmentation engine. As reported by GangMin Kim, if such packet is that may cause a UaF when the defrag engine later on tries to tuch again such packet."

act_ct was never meant to be used in the egress path, however some users are attaching it to egress today [2]. Attempting to reach a middle ground, we noticed that, while most qdiscs are not handling TC_ACT_CONSUMED, clsact/ingress qdiscs are. With that in mind, we address the issue by only allowing act_ct to bind to clsact/ingress qdiscs and shared blocks. That way it's still possible to attach act_ct to egress (albeit only with clsact).

[1] https://lore.kernel.org/netdev/674b8cbfc385c6f37fb29a1de08d8fe5c2b0fbee.1771321118.git.pabeni@redhat.com/ [2] https://lore.kernel.org/netdev/cc6bfb4a-4a2b-42d8-b9ce-7ef6644fb22b@ovn.org/

Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Show details on source website
To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2026-23270"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-416"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-03-18T18:16:26Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared blocks\n\nAs Paolo said earlier [1]:\n\n\"Since the blamed commit below, classify can return TC_ACT_CONSUMED while\nthe current skb being held by the defragmentation engine. As reported by\nGangMin Kim, if such packet is that may cause a UaF when the defrag engine\nlater on tries to tuch again such packet.\"\n\nact_ct was never meant to be used in the egress path, however some users\nare attaching it to egress today [2]. Attempting to reach a middle\nground, we noticed that, while most qdiscs are not handling\nTC_ACT_CONSUMED, clsact/ingress qdiscs are. With that in mind, we\naddress the issue by only allowing act_ct to bind to clsact/ingress\nqdiscs and shared blocks. That way it\u0027s still possible to attach act_ct to\negress (albeit only with clsact).\n\n[1] https://lore.kernel.org/netdev/674b8cbfc385c6f37fb29a1de08d8fe5c2b0fbee.1771321118.git.pabeni@redhat.com/\n[2] https://lore.kernel.org/netdev/cc6bfb4a-4a2b-42d8-b9ce-7ef6644fb22b@ovn.org/",
  "id": "GHSA-62jp-jvc3-7hh9",
  "modified": "2026-07-14T15:31:40Z",
  "published": "2026-03-18T18:31:18Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23270"
    },
    {
      "type": "WEB",
      "url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
    },
    {
      "type": "WEB",
      "url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/11cb63b0d1a0685e0831ae3c77223e002ef18189"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/380ad8b7c65ea7aa10ef2258297079ed5ac1f5b6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/524ce8b4ea8f64900b6c52b6a28df74f6bc0801e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5a110ddcc99bda77a28598b3555fe009eaab3828"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9deda0fcda5c1f388c5e279541850b71a2ccfcf4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bc4e5bb529823a09f02dbe96169de679a9db26e0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fb3c380a54e33d1fd272cc342faa906d787d7ef1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





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.


Detection rules are retrieved from Rulezet.


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.