CVE-2025-38457
net/sched: Abort __tc_modify_qdisc if parent class does not exist
- Published
- Updated
- Reserved
- Assigned by
- Linux
Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: Abort __tc_modify_qdisc if parent class does not exist Lion's patch [1] revealed an ancient bug in the qdisc API. Whenever a user creates/modifies a qdisc specifying as a parent another qdisc, the qdisc API will, during grafting, detect that the user is not trying to attach to a class and reject. However grafting is performed after qdisc_create (and thus the qdiscs' init callback) is executed. In qdiscs that eventually call qdisc_tree_reduce_backlog during init or change (such as fq, hhf, choke, etc), an issue arises. For example, executing the following commands: sudo tc qdisc add dev lo root handle a: htb default 2 sudo tc qdisc add dev lo parent a: handle beef fq Qdiscs such as fq, hhf, choke, etc unconditionally invoke qdisc_tree_reduce_backlog() in their control path init() or change() which then causes a failure to find the child class; however, that does not stop the unconditional invocation of the assumed child qdisc's qlen_notify with a null class. All these qdiscs make the assumption that class is non-null. The solution is ensure that qdisc_leaf() which looks up the parent class, and is invoked prior to qdisc_create(), should return failure on not finding the class. In this patch, we leverage qdisc_leaf to return ERR_PTRs whenever the parentid doesn't correspond to a class, so that we can detect it earlier on and abort before qdisc_create is called. [1] https://lore.kernel.org/netdev/[email protected]/
Timeline
ID reserved
By Linux
- 3 months later
· 3 months later
Published
- 16 months later
· 16 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | Medium5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.20% · top 91% of all CVEs (9 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.5.
Affected products
- affected 5e50da01d0ce7ef0ba3ed6cfabd62f327da0aca6 – < 923a276c74e25073ae391e930792ac86a9f77f1e
- affected 5e50da01d0ce7ef0ba3ed6cfabd62f327da0aca6 – < 90436e72c9622c2f70389070088325a3232d339f
- affected 5e50da01d0ce7ef0ba3ed6cfabd62f327da0aca6 – < 25452638f133ac19d75af3f928327d8016952c8e
- affected 5e50da01d0ce7ef0ba3ed6cfabd62f327da0aca6 – < 23c165dde88eac405eebb59051ea1fe139a45803
- affected 5e50da01d0ce7ef0ba3ed6cfabd62f327da0aca6 – < 4c691d1b6b6dbd73f30ed9ee7da05f037b0c49af
- affected 5e50da01d0ce7ef0ba3ed6cfabd62f327da0aca6 – < 8ecd651ef24ab50123692a4e3e25db93cb11602a
- affected 5e50da01d0ce7ef0ba3ed6cfabd62f327da0aca6 – < e28a383d6485c3bb51dc5953552f76c4dea33eea
- affected 5e50da01d0ce7ef0ba3ed6cfabd62f327da0aca6 – < ffdde7bf5a439aaa1955ebd581f5c64ab1533963
- affected 2.6.20
- unaffected < 2.6.20
- unaffected 5.4.296 – ≤ 5.4.*
- unaffected 5.10.240 – ≤ 5.10.*
- unaffected 5.15.189 – ≤ 5.15.*
- unaffected 6.1.146 – ≤ 6.1.*
- unaffected 6.6.99 – ≤ 6.6.*
- unaffected 6.12.39 – ≤ 6.12.*
- unaffected 6.15.7 – ≤ 6.15.*
- unaffected 6.16 – ≤ *
References (11)
- https://git.kernel.org/stable/c/923a276c74e25073ae391e930792ac86a9f77f1e (opens in a new tab)
- https://git.kernel.org/stable/c/90436e72c9622c2f70389070088325a3232d339f (opens in a new tab)
- https://git.kernel.org/stable/c/25452638f133ac19d75af3f928327d8016952c8e (opens in a new tab)
- https://git.kernel.org/stable/c/23c165dde88eac405eebb59051ea1fe139a45803 (opens in a new tab)
- https://git.kernel.org/stable/c/4c691d1b6b6dbd73f30ed9ee7da05f037b0c49af (opens in a new tab)
- https://git.kernel.org/stable/c/8ecd651ef24ab50123692a4e3e25db93cb11602a (opens in a new tab)
- https://git.kernel.org/stable/c/e28a383d6485c3bb51dc5953552f76c4dea33eea (opens in a new tab)
- https://git.kernel.org/stable/c/ffdde7bf5a439aaa1955ebd581f5c64ab1533963 (opens in a new tab)
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html (opens in a new tab)
- https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html (opens in a new tab)
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
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[](https://cveledger.app/cve/CVE-2025-38457)Record last updated .