Vulnerability · Published Oct 4, 2025 · Assigned by Linux
CVE-2025-39946tls: make sure to abort the stream if headers are bogus
Critical 9.8
In plain English
A critical-severity security flaw 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 10.3% (higher than 96% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.
Official description
In the Linux kernel, the following vulnerability has been resolved: tls: make sure to abort the stream if headers are bogus Normally we wait for the socket to buffer up the whole record before we service it. If the socket has a tiny buffer, however, we read out the data sooner, to prevent connection stalls. Make sure that we abort the connection when we find out late that the record is actually invalid. Retrying the parsing is fine in itself but since we copy some more data each time before we parse we can overflow the allocated skb space. Constructing a scenario in which we're under pressure without enough data in the socket to parse the length upfront is quite hard. syzbot figured out a way to do this by serving us the header in small OOB sends, and then filling in the recvbuf with a large normal send. Make sure that tls_rx_msg_size() aborts strp, if we reach an invalid record there's really no way to recover.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | linux | 6.1.158-1 | DSA-6053-1 |
| Debian:12 | linux | 6.1.158-1 | DEBIAN-CVE-2025-39946 |
| Debian:13 | linux | 6.12.57-1 | DEBIAN-CVE-2025-39946 |
| Debian:14 | linux | 6.16.9-1 | DEBIAN-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux | 6.8.0-100.100 | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-allwinner-5.19 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-aws | 6.8.0-1046.49 | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-aws-5.19 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-aws-6.14 | 6.14.0-1018.18~24.04.1 | USN-7921-1 |
| Ubuntu:24.04:LTS | linux-aws-6.14 | 6.14.0-1018.18~24.04.1 | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-aws-6.2 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-aws-6.5 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-aws-6.8 | 6.8.0-1046.49~22.04.1 | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-azure | 6.8.0-1046.52 | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-azure-5.19 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-azure-6.11 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-azure-6.14 | 6.14.0-1017.17~24.04.1 | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-azure-6.2 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-azure-6.5 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-azure-6.8 | 6.8.0-1051.57~22.04.1 | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-azure-fde | 6.8.0-1046.53 | UBUNTU-CVE-2025-39946 |
| Ubuntu:25.10 | linux-azure-fde | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-azure-fde-5.19 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-azure-fde-6.14 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-azure-fde-6.2 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-azure-fde-6.8 | 6.8.0-1046.53~22.04.1 | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-azure-nvidia | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-azure-nvidia-6.14 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-gcp | 6.8.0-1047.50 | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-gcp-5.19 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-gcp-6.11 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-gcp-6.14 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-gcp-6.2 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-gcp-6.5 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-gcp-6.8 | 6.8.0-1047.50~22.04.2 | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-gke | 6.8.0-1043.48 | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-gkeop | 6.8.0-1030.33 | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-hwe-5.19 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-hwe-6.11 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-hwe-6.14 | 6.14.0-37.37~24.04.1 | USN-7921-1 |
| Ubuntu:22.04:LTS | linux-hwe-6.2 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-hwe-6.5 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-hwe-6.8 | 6.8.0-100.100~22.04.1 | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-ibm | 6.8.0-1044.44 | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-ibm-6.8 | 6.8.0-1044.44~22.04.1 | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-intel | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-intel-iot-realtime | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-lowlatency | 6.8.0-100.100.1 | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-lowlatency-hwe-5.19 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-lowlatency-hwe-6.11 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-lowlatency-hwe-6.2 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-lowlatency-hwe-6.5 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-lowlatency-hwe-6.8 | 6.8.0-100.100.1~22.04.1 | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-nvidia | 6.8.0-1046.49 | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-nvidia-6.11 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-nvidia-6.2 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-nvidia-6.5 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-nvidia-6.8 | 6.8.0-1046.49~22.04.1 | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-nvidia-lowlatency | 6.8.0-1046.49.1 | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-nvidia-tegra | 6.8.0-1020.20 | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-oem-5.17 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-oem-6.0 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-oem-6.1 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-oem-6.11 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-oem-6.14 | 6.14.0-1017.17 | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-oem-6.14 | 6.14.0-1017.17 | USN-7936-1 |
| Ubuntu:22.04:LTS | linux-oem-6.5 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-oem-6.8 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-oracle | 6.8.0-1043.44 | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-oracle-6.14 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-oracle-6.5 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-oracle-6.8 | 6.8.0-1043.44~22.04.1 | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-raspi | 6.8.0-1047.51 | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-raspi-realtime | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-realtime | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-realtime | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-riscv | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-riscv | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-riscv-5.19 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-riscv-6.14 | 6.14.0-37.37.1~24.04.1 | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-riscv-6.5 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-riscv-6.8 | 6.8.0-100.100~22.04.1 | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-starfive-5.19 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-starfive-6.2 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:22.04:LTS | linux-starfive-6.5 | no fix listed | UBUNTU-CVE-2025-39946 |
| Ubuntu:24.04:LTS | linux-xilinx | 6.8.0-1023.24 | UBUNTU-CVE-2025-39946 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Linux | Linux | 84c61fe1a75b4255df1e1e7c054c9e6d048da417 – before b36462146d86b1f22e594fe4dae611dffacfb20384c61fe1a75b4255df1e1e7c054c9e6d048da417 – before 4cefe5be73886f383639fe0850bb72d5b568a7b984c61fe1a75b4255df1e1e7c054c9e6d048da417 – before 208640e6225cc929a05adbf79d1df558add3e23184c61fe1a75b4255df1e1e7c054c9e6d048da417 – before 61ca2da5fb8f433ce8bbd1657c84a86272133e6b84c61fe1a75b4255df1e1e7c054c9e6d048da417 – before 0aeb54ac4cd5cf8f60131b4d9ec0b6dc9c27b20d |
| Linux | Linux | 6.0 |
References
- https://git.kernel.org/stable/c/b36462146d86b1f22e594fe4dae611dffacfb203
- https://git.kernel.org/stable/c/4cefe5be73886f383639fe0850bb72d5b568a7b9
- https://git.kernel.org/stable/c/208640e6225cc929a05adbf79d1df558add3e231
- https://git.kernel.org/stable/c/61ca2da5fb8f433ce8bbd1657c84a86272133e6b
- https://git.kernel.org/stable/c/0aeb54ac4cd5cf8f60131b4d9ec0b6dc9c27b20d