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Vulnerability · Published Feb 18, 2025 · Assigned by Linux

CVE-2025-21703netem: Update sch->q.qlen before qdisc_tree_reduce_backlog()

High 7.8

In plain English

A high-severity use-after-free in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 23% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.8High
Exploit odds (30 days)0.3%top 76.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

In the Linux kernel, the following vulnerability has been resolved: netem: Update sch->q.qlen before qdisc_tree_reduce_backlog() qdisc_tree_reduce_backlog() notifies parent qdisc only if child qdisc becomes empty, therefore we need to reduce the backlog of the child qdisc before calling it. Otherwise it would miss the opportunity to call cops->qlen_notify(), in the case of DRR, it resulted in UAF since DRR uses ->qlen_notify() to maintain its active list.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12linux6.1.129-1DEBIAN-CVE-2025-21703
Debian:13linux6.12.15-1DEBIAN-CVE-2025-21703
Debian:14linux6.12.15-1DEBIAN-CVE-2025-21703
Ubuntu:22.04:LTSlinux5.15.0-138.148UBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux5.15.0-138.148USN-7455-1
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-aws5.15.0-1082.89USN-7455-1
Ubuntu:22.04:LTSlinux-aws5.15.0-1082.89UBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-azure5.15.0-1087.96USN-7455-1
Ubuntu:22.04:LTSlinux-azure5.15.0-1087.96UBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2025-21703
Ubuntu:24.04:LTSlinux-azure-6.116.11.0-1013.13~24.04.1UBUNTU-CVE-2025-21703
Ubuntu:24.04:LTSlinux-azure-6.116.11.0-1013.13~24.04.1USN-7448-1
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-azure-fde5.15.0-1087.96.1USN-7455-1
Ubuntu:22.04:LTSlinux-azure-fde5.15.0-1087.96.1UBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-gcp5.15.0-1081.90UBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-gcp5.15.0-1081.90USN-7455-1
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2025-21703
Ubuntu:24.04:LTSlinux-gcp-6.116.11.0-1013.13~24.04.1UBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-gke5.15.0-1079.85USN-7455-1
Ubuntu:22.04:LTSlinux-gke5.15.0-1079.85UBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-gkeop5.15.0-1064.72USN-7455-1
Ubuntu:22.04:LTSlinux-gkeop5.15.0-1064.72UBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2025-21703
Ubuntu:24.04:LTSlinux-hwe-6.116.11.0-24.24~24.04.1USN-7445-1
Ubuntu:24.04:LTSlinux-hwe-6.116.11.0-24.24~24.04.1UBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-ibm5.15.0-1074.77USN-7455-1
Ubuntu:22.04:LTSlinux-ibm5.15.0-1074.77UBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-intel-iotg5.15.0-1077.83UBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-intel-iotg5.15.0-1077.83USN-7455-1
Ubuntu:22.04:LTSlinux-kvm5.15.0-1078.83UBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-kvm5.15.0-1078.83USN-7455-1
Ubuntu:22.04:LTSlinux-lowlatency5.15.0-138.148UBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-lowlatency5.15.0-138.148USN-7455-1
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2025-21703
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.116.11.0-1012.13~24.04.1UBUNTU-CVE-2025-21703
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.116.11.0-1012.13~24.04.1USN-7445-1
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-nvidia5.15.0-1076.77UBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-nvidia5.15.0-1076.77USN-7455-1
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-nvidia-tegra5.15.0-1035.35UBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-nvidia-tegra5.15.0-1035.35USN-7455-1
Ubuntu:22.04:LTSlinux-nvidia-tegra-igx5.15.0-1023.23USN-7455-1
Ubuntu:22.04:LTSlinux-nvidia-tegra-igx5.15.0-1023.23UBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2025-21703
Ubuntu:24.04:LTSlinux-oem-6.116.11.0-1020.20USN-7445-1
Ubuntu:24.04:LTSlinux-oem-6.116.11.0-1020.20UBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-oracle5.15.0-1079.85UBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-oracle5.15.0-1079.85USN-7455-1
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-raspi5.15.0-1076.79USN-7455-1
Ubuntu:22.04:LTSlinux-raspi5.15.0-1076.79UBUNTU-CVE-2025-21703
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-xilinx-zynqmp5.15.0-1046.50UBUNTU-CVE-2025-21703
Ubuntu:22.04:LTSlinux-xilinx-zynqmp5.15.0-1046.50USN-7475-1

Affected products (as reported)

VendorProductVersions
Linux Linux 83c6ab12f08dcc09d4c5ac86fdb89736b28f1d31 – before e395fec75ac2dbffc99b4bce57b7f1f3c5449f2c216509dda290f6db92c816dd54b83c1df9da9e76 – before 7f31d74fcc556a9166b1bb20515542de7bb939d1c2047b0e216c8edce227d7c42f99ac2877dad0e4 – before 98a2c685293aae122f688cde11d9334dddc5d20710df49cfca73dfbbdb6c4150d859f7e8926ae427 – before 7b79ca9a1de6a428d486ff52fb3d602321c08f553824c5fad18eeb7abe0c4fc966f29959552dca3e – before 1f8e3f4a4b8b90ad274dfbc66fc7d55cb582f4d5356078a5c55ec8d2061fcc009fb8599f5b0527f9 – before 6312555249082d6d8cc5321ff725df05482d8b83f8d4bc455047cf3903cd6f85f49978987dbb3027 – before 839ecc583fa00fab785fde1c85a326743657fd32f8d4bc455047cf3903cd6f85f49978987dbb3027 – before 638ba5089324796c2ee49af10427459c2de35f71
Linux Linux 6.13

Weakness: CWE-416 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References