net/sched: Enforce that teql can only be used as root qdisc
Summary
| CVE | CVE-2026-23074 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-02-04 17:16:18 UTC |
| Updated | 2026-07-15 02:18:39 UTC |
| Description | In the Linux kernel, the following vulnerability has been resolved: net/sched: Enforce that teql can only be used as root qdisc Design intent of teql is that it is only supposed to be used as root qdisc. We need to check for that constraint. Although not important, I will describe the scenario that unearthed this issue for the curious. GangMin Kim <[email protected]> managed to concot a scenario as follows: ROOT qdisc 1:0 (QFQ) ├── class 1:1 (weight=15, lmax=16384) netem with delay 6.4s └── class 1:2 (weight=1, lmax=1514) teql GangMin sends a packet which is enqueued to 1:1 (netem). Any invocation of dequeue by QFQ from this class will not return a packet until after 6.4s. In the meantime, a second packet is sent and it lands on 1:2. teql's enqueue will return success and this will activate class 1:2. Main issue is that teql only updates the parent visible qlen (sch->q.qlen) at dequeue. Since QFQ will only call dequeue if peek succeeds (and teql's peek always returns NULL), dequeue will never be called and thus the qlen will remain as 0. With that in mind, when GangMin updates 1:2's lmax value, the qfq_change_class calls qfq_deact_rm_from_agg. Since the child qdisc's qlen was not incremented, qfq fails to deactivate the class, but still frees its pointers from the aggregate. So when the first packet is rescheduled after 6.4 seconds (netem's delay), a dangling pointer is accessed causing GangMin's causing a UAF. |
Risk And Classification
Primary CVSS: v3.1 7.8 HIGH from [email protected]
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Problem Types: CWE-416 | CWE-825 | CWE-825 Expired Pointer Dereference
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Primary | 7.8 | HIGH | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | ADP | CVSS | 7 | HIGH | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | Secondary | 7.8 | HIGH | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | Secondary | 7 | HIGH | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | CNA | DECLARED | 7.8 | HIGH | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
CVSS v3.1 Breakdown
Attack Vector
LocalAttack Complexity
LowPrivileges Required
LowUser Interaction
NoneScope
UnchangedConfidentiality
HighIntegrity
HighAvailability
HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Operating System | Linux | Linux Kernel | All | All | All | All |
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 73d970ff0eddd874a84c953387c7f4464b705fc6 git | Not specified |
| CNA | Linux | Linux | affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 ae810e6a8ac4fe25042e6825d2a401207a2e41fb git | Not specified |
| CNA | Linux | Linux | affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 dad49a67c2d817bfec98e6e45121b351e3a0202c git | Not specified |
| CNA | Linux | Linux | affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 0686bedfed34155520f3f735cbf3210cb9044380 git | Not specified |
| CNA | Linux | Linux | affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 4c7e8aa71c9232cba84c289b4b56cba80b280841 git | Not specified |
| CNA | Linux | Linux | affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 16ed73c1282d376b956bff23e5139add061767ba git | Not specified |
| CNA | Linux | Linux | affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 50da4b9d07a7a463e2cfb738f3ad4cff6b2c9c3b git | Not specified |
| CNA | Linux | Linux | affected 2.6.12 | Not specified |
| CNA | Linux | Linux | unaffected 2.6.12 semver | Not specified |
| CNA | Linux | Linux | unaffected 5.10.249 5.10.* semver | Not specified |
| CNA | Linux | Linux | unaffected 5.15.199 5.15.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.1.162 6.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.6.122 6.6.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.68 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.8 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.19 * original_commit_for_fix | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 6 Extended Lifecycle Support - EXTENSION | unaffected 0:2.6.32-754.59.1.el6 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 7 Extended Lifecycle Support | unaffected 0:3.10.0-1160.147.1.rt56.1299.el7 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 7 Extended Lifecycle Support | unaffected 0:3.10.0-1160.147.1.el7 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8 | unaffected 0:4.18.0-553.107.1.rt7.448.el8_10 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8 | unaffected 0:4.18.0-553.107.1.el8_10 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.2 Advanced Update Support | unaffected 0:4.18.0-193.187.1.el8_2 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | unaffected 0:4.18.0-305.186.1.el8_4 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On | unaffected 0:4.18.0-305.186.1.el8_4 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support | unaffected 0:4.18.0-372.181.1.el8_6 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.6 Telecommunications Update Service | unaffected 0:4.18.0-372.181.1.el8_6 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.6 Update Services For SAP Solutions | unaffected 0:4.18.0-372.181.1.el8_6 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.8 Telecommunications Update Service | unaffected 0:4.18.0-477.130.1.el8_8 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 8.8 Update Services For SAP Solutions | unaffected 0:4.18.0-477.130.1.el8_8 * rpm | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 10 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 9 | Not specified | Not specified |
| ADP | Red Hat | Red Hat Enterprise Linux 9 | Not specified | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23074.json | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | security.access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:3268 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:3360 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:3277 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| git.kernel.org/stable/c/ae810e6a8ac4fe25042e6825d2a401207a2e41fb | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | Patch |
| access.redhat.com/errata/RHSA-2026:3110 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| git.kernel.org/stable/c/16ed73c1282d376b956bff23e5139add061767ba | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | Patch |
| git.kernel.org/stable/c/0686bedfed34155520f3f735cbf3210cb9044380 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | Patch |
| git.kernel.org/stable/c/73d970ff0eddd874a84c953387c7f4464b705fc6 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | Patch |
| git.kernel.org/stable/c/4c7e8aa71c9232cba84c289b4b56cba80b280841 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | Patch |
| access.redhat.com/errata/RHSA-2026:3634 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| bugzilla.redhat.com/show_bug.cgi | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | bugzilla.redhat.com | |
| access.redhat.com/errata/RHSA-2026:3388 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| git.kernel.org/stable/c/50da4b9d07a7a463e2cfb738f3ad4cff6b2c9c3b | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | Patch |
| access.redhat.com/errata/RHSA-2026:3083 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/security/cve/CVE-2026-23074 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| git.kernel.org/stable/c/dad49a67c2d817bfec98e6e45121b351e3a0202c | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | Patch |
| access.redhat.com/errata/RHSA-2026:3685 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:3810 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | access.redhat.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| ADP | 2026-02-04T00:00:00.000Z | Reported to Red Hat. |
| ADP | 2026-02-04T00:00:00.000Z | Made public. |
Solutions
ADP: RHSA-2026:3810: Red Hat Enterprise Linux Server -EXTENSION(v. 6 ELS-EXTENSION), Red Hat Enterprise Linux Server Optional -EXTENSION (v. 6 ELS -EXTENSION)
ADP: RHSA-2026:3685: Red Hat Enterprise Linux Server (v. 7 ELS), Red Hat Enterprise Linux Server Optional (v. 7 ELS)
ADP: RHSA-2026:3634: Red Hat Enterprise Linux for Real Time (v. 7 ELS)
ADP: RHSA-2026:3083: Red Hat Enterprise Linux BaseOS (v. 8), Red Hat Enterprise Linux CRB (v. 8)
ADP: RHSA-2026:3388: Red Hat Enterprise Linux BaseOS AUS (v. 8.2)
ADP: RHSA-2026:3360: Red Hat Enterprise Linux BaseOS AUS (v.8.4), Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.4)
ADP: RHSA-2026:3268: Red Hat Enterprise Linux BaseOS AUS (v.8.6), Red Hat Enterprise Linux BaseOS E4S (v.8.6), Red Hat Enterprise Linux BaseOS TUS (v.8.6)
ADP: RHSA-2026:3277: Red Hat Enterprise Linux BaseOS E4S (v.8.8), Red Hat Enterprise Linux BaseOS TUS (v.8.8)
ADP: RHSA-2026:3110: Red Hat Enterprise Linux NFV (v. 8), Red Hat Enterprise Linux RT (v. 8)
There are currently no legacy QID mappings associated with this CVE.