🛡️ CVE-2025-39946 on Ubuntu — linux
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.
Distribution advisory
This page covers CVE-2025-39946 as tracked by Ubuntu, for the package linux. The fix is available in version 6.8.0-100.100; earlier versions remain affected.
How this vulnerability can be exploited
This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.
CVSS metrics in full
The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Attack vector: Network — reachable from anywhere that can route to the service.
- Attack complexity: Low — the attack works reliably, with no preparation.
- Privileges required: None — an unauthenticated stranger can try it.
- User interaction: None — nobody has to be tricked into anything.
- Scope: Unchanged — the damage stays inside the vulnerable component.
- Confidentiality impact: High — total loss, or loss the attacker controls.
- Integrity impact: High — total loss, or loss the attacker controls.
- Availability impact: High — total loss, or loss the attacker controls.
Affected software
UBUNTU-CVE-2025-39946 is recorded against 121 packages.
- linux (fixed in 6.8.0-100.100)
- linux-allwinner-5.19
- linux-aws (fixed in 6.8.0-1046.49)
- linux-aws-5.0
- linux-aws-5.11
- linux-aws-5.13
- linux-aws-5.19
- linux-aws-5.3
- linux-aws-5.8
- linux-aws-6.14 (fixed in 6.14.0-1018.18~24.04.1)
- linux-aws-6.2
- linux-aws-6.5
- linux-aws-6.8 (fixed in 6.8.0-1046.49~22.04.1)
- linux-aws-fips (fixed in 6.8.0-1046.49+fips1)
- linux-azure (fixed in 6.8.0-1046.52)
- linux-azure-5.11
- linux-azure-5.13
- linux-azure-5.19
- linux-azure-5.3
- linux-azure-5.8
- linux-azure-6.11
- linux-azure-6.14 (fixed in 6.14.0-1017.17~24.04.1)
- linux-azure-6.2
- linux-azure-6.5
Show the remaining 97 packages
- linux-azure-6.8 (fixed in 6.8.0-1051.57~22.04.1)
- linux-azure-edge
- linux-azure-fde
- linux-azure-fde-5.19
- linux-azure-fde-6.14
- linux-azure-fde-6.2
- linux-azure-fde-6.8
- linux-azure-fips (fixed in 6.8.0-1046.52+fips1)
- linux-azure-nvidia
- linux-azure-nvidia-6.14
- linux-bluefield
- linux-fips (fixed in 6.8.0-100.100+fips1)
- linux-gcp (fixed in 6.8.0-1047.50)
- linux-gcp-5.11
- linux-gcp-5.13
- linux-gcp-5.19
- linux-gcp-5.3
- linux-gcp-5.8
- linux-gcp-6.11
- linux-gcp-6.14
- linux-gcp-6.2
- linux-gcp-6.5
- linux-gcp-6.8 (fixed in 6.8.0-1047.50~22.04.2)
- linux-gcp-fips (fixed in 6.8.0-1047.50+fips1)
- linux-gke (fixed in 6.8.0-1043.48)
- linux-gke-4.15
- linux-gke-5.15
- linux-gke-5.4
- linux-gkeop (fixed in 6.8.0-1030.33)
- linux-gkeop-5.15
- linux-gkeop-5.4
- linux-hwe
- linux-hwe-5.11
- linux-hwe-5.13
- linux-hwe-5.19
- linux-hwe-5.8
- linux-hwe-6.11
- linux-hwe-6.2
- linux-hwe-6.5
- linux-hwe-6.8 (fixed in 6.8.0-100.100~22.04.1)
- linux-hwe-edge
- linux-ibm (fixed in 6.8.0-1044.44)
- linux-ibm-6.8 (fixed in 6.8.0-1044.44~22.04.1)
- linux-intel
- linux-intel-5.13
- linux-intel-iot-realtime
- linux-lowlatency (fixed in 6.8.0-100.100.1)
- linux-lowlatency-hwe-5.19
- linux-lowlatency-hwe-6.11
- linux-lowlatency-hwe-6.2
- linux-lowlatency-hwe-6.5
- linux-lowlatency-hwe-6.8 (fixed in 6.8.0-100.100.1~22.04.1)
- linux-nvidia (fixed in 6.8.0-1046.49)
- linux-nvidia-6.11
- linux-nvidia-6.2
- linux-nvidia-6.5
- linux-nvidia-6.8 (fixed in 6.8.0-1046.49~22.04.1)
- linux-nvidia-lowlatency (fixed in 6.8.0-1046.49.1)
- linux-nvidia-tegra (fixed in 6.8.0-1020.20)
- linux-oem
- linux-oem-5.10
- linux-oem-5.13
- linux-oem-5.14
- linux-oem-5.17
- linux-oem-5.6
- linux-oem-6.0
- linux-oem-6.1
- linux-oem-6.11
- linux-oem-6.14 (fixed in 6.14.0-1017.17)
- linux-oem-6.5
- linux-oem-6.8
- linux-oracle (fixed in 6.8.0-1043.44)
- linux-oracle-5.0
- linux-oracle-5.11
- linux-oracle-5.13
- linux-oracle-5.3
- linux-oracle-5.8
- linux-oracle-6.14
- linux-oracle-6.5
- linux-oracle-6.8 (fixed in 6.8.0-1043.44~22.04.1)
- linux-raspi (fixed in 6.8.0-1047.51)
- linux-raspi-realtime (fixed in 6.8.0-2037.38)
- linux-raspi2
- linux-realtime (fixed in 6.8.1-1041.42)
- linux-realtime-6.14 (fixed in 6.14.0-1017.17~24.04.1)
- linux-realtime-6.8 (fixed in 6.8.1-1041.42~22.04.1)
- linux-riscv
- linux-riscv-5.11
- linux-riscv-5.19
- linux-riscv-5.8
- linux-riscv-6.14 (fixed in 6.14.0-37.37.1~24.04.1)
- linux-riscv-6.5
- linux-riscv-6.8 (fixed in 6.8.0-100.100~22.04.1)
- linux-starfive-5.19
- linux-starfive-6.2
- linux-starfive-6.5
- linux-xilinx (fixed in 6.8.0-1023.24)
Timeline and source
Published on 4 October 2025 and last revised on 17 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.
References
ubuntu.com (Report)
www.cve.org (Report)
git.kernel.org (Report)
git.kernel.org (Report)
git.kernel.org (Report)
git.kernel.org (Report)
git.kernel.org (Report)
git.kernel.org (Report)
ubuntu.com (Advisory)
ubuntu.com (Advisory)
ubuntu.com (Advisory)
ubuntu.com (Advisory)
ubuntu.com (Advisory)
ubuntu.com (Advisory)
ubuntu.com (Advisory)
ubuntu.com (Advisory)
ubuntu.com (Advisory)
ubuntu.com (Advisory)
ubuntu.com (Advisory)
ubuntu.com (Advisory)
ubuntu.com (Advisory)
ubuntu.com (Advisory)
ubuntu.com (Advisory)
ubuntu.com (Advisory)
ubuntu.com (Advisory)
ubuntu.com (Advisory)
ubuntu.com (Advisory)
ubuntu.com (Advisory)
Other advisories for this package
linux has other advisories on record. If you are patching this one, these are worth checking on the same host:
- DEBIAN-CVE-2022-4994 (published 30 Jul 2026)
- CVE-2026-35233 (4.4 Medium, published 1 May 2026)
- CVE-2026-21996 (3.3 Low, published 1 May 2026)
- CVE-2026-21991 (5.5 Medium, published 16 Mar 2026)
- CGA-w6xv-3fg4-grm5 (published 29 Jan 2026)
- CGA-mcwh-q4vm-9f29 (published 29 Jan 2026)
- CGA-wf5v-37v7-wvrh (published 7 Jan 2026)
- CGA-58q9-gmq4-72q9 (published 7 Jan 2026)
CVE-2025-39946 on other distributions
Each distribution ships its own build and its own fixed version. Pick the one you run:
Details
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| linux | — | 6.8.0-100.100 |
| linux-allwinner-5.19 | — | — |
| linux-aws | — | 6.8.0-1046.49 |
| linux-aws-5.0 | — | — |
| linux-aws-5.11 | — | — |
| linux-aws-5.13 | — | — |
| linux-aws-5.19 | — | — |
| linux-aws-5.3 | — | — |
| linux-aws-5.8 | — | — |
| linux-aws-6.14 | — | 6.14.0-1018.18~24.04.1 |
| linux-aws-6.2 | — | — |
| linux-aws-6.5 | — | — |
| linux-aws-6.8 | — | 6.8.0-1046.49~22.04.1 |
| linux-aws-fips | — | 6.8.0-1046.49+fips1 |
| linux-azure | — | 6.8.0-1046.52 |
| linux-azure-5.11 | — | — |
| linux-azure-5.13 | — | — |
| linux-azure-5.19 | — | — |
| linux-azure-5.3 | — | — |
| linux-azure-5.8 | — | — |
| linux-azure-6.11 | — | — |
| linux-azure-6.14 | — | 6.14.0-1017.17~24.04.1 |
| linux-azure-6.2 | — | — |
| linux-azure-6.5 | — | — |
| linux-azure-6.8 | — | 6.8.0-1051.57~22.04.1 |
| linux-azure-edge | — | — |
| linux-azure-fde | — | — |
| linux-azure-fde-5.19 | — | — |
| linux-azure-fde-6.14 | — | — |
| linux-azure-fde-6.2 | — | — |
| linux-azure-fde-6.8 | — | — |
| linux-azure-fips | — | 6.8.0-1046.52+fips1 |
| linux-azure-nvidia | — | — |
| linux-azure-nvidia-6.14 | — | — |
| linux-bluefield | — | — |
| linux-fips | — | 6.8.0-100.100+fips1 |
| linux-gcp | — | 6.8.0-1047.50 |
| linux-gcp-5.11 | — | — |
| linux-gcp-5.13 | — | — |
| linux-gcp-5.19 | — | — |
| linux-gcp-5.3 | — | — |
| linux-gcp-5.8 | — | — |
| linux-gcp-6.11 | — | — |
| linux-gcp-6.14 | — | — |
| linux-gcp-6.2 | — | — |
| linux-gcp-6.5 | — | — |
| linux-gcp-6.8 | — | 6.8.0-1047.50~22.04.2 |
| linux-gcp-fips | — | 6.8.0-1047.50+fips1 |
| linux-gke | — | 6.8.0-1043.48 |
| linux-gke-4.15 | — | — |
| linux-gke-5.15 | — | — |
| linux-gke-5.4 | — | — |
| linux-gkeop | — | 6.8.0-1030.33 |
| linux-gkeop-5.15 | — | — |
| linux-gkeop-5.4 | — | — |
| linux-hwe | — | — |
| linux-hwe-5.11 | — | — |
| linux-hwe-5.13 | — | — |
| linux-hwe-5.19 | — | — |
| linux-hwe-5.8 | — | — |
| linux-hwe-6.11 | — | — |
| linux-hwe-6.2 | — | — |
| linux-hwe-6.5 | — | — |
| linux-hwe-6.8 | — | 6.8.0-100.100~22.04.1 |
| linux-hwe-edge | — | — |
| linux-ibm | — | 6.8.0-1044.44 |
| linux-ibm-6.8 | — | 6.8.0-1044.44~22.04.1 |
| linux-intel | — | — |
| linux-intel-5.13 | — | — |
| linux-intel-iot-realtime | — | — |
| linux-lowlatency | — | 6.8.0-100.100.1 |
| linux-lowlatency-hwe-5.19 | — | — |
| linux-lowlatency-hwe-6.11 | — | — |
| linux-lowlatency-hwe-6.2 | — | — |
| linux-lowlatency-hwe-6.5 | — | — |
| linux-lowlatency-hwe-6.8 | — | 6.8.0-100.100.1~22.04.1 |
| linux-nvidia | — | 6.8.0-1046.49 |
| linux-nvidia-6.11 | — | — |
| linux-nvidia-6.2 | — | — |
| linux-nvidia-6.5 | — | — |
| linux-nvidia-6.8 | — | 6.8.0-1046.49~22.04.1 |
| linux-nvidia-lowlatency | — | 6.8.0-1046.49.1 |
| linux-nvidia-tegra | — | 6.8.0-1020.20 |
| linux-oem | — | — |
| linux-oem-5.10 | — | — |
| linux-oem-5.13 | — | — |
| linux-oem-5.14 | — | — |
| linux-oem-5.17 | — | — |
| linux-oem-5.6 | — | — |
| linux-oem-6.0 | — | — |
| linux-oem-6.1 | — | — |
| linux-oem-6.11 | — | — |
| linux-oem-6.14 | — | 6.14.0-1017.17 |
| linux-oem-6.5 | — | — |
| linux-oem-6.8 | — | — |
| linux-oracle | — | 6.8.0-1043.44 |
| linux-oracle-5.0 | — | — |
| linux-oracle-5.11 | — | — |
| linux-oracle-5.13 | — | — |
| linux-oracle-5.3 | — | — |
| linux-oracle-5.8 | — | — |
| linux-oracle-6.14 | — | — |
| linux-oracle-6.5 | — | — |
| linux-oracle-6.8 | — | 6.8.0-1043.44~22.04.1 |
| linux-raspi | — | 6.8.0-1047.51 |
| linux-raspi-realtime | — | 6.8.0-2037.38 |
| linux-raspi2 | — | — |
| linux-realtime | — | 6.8.1-1041.42 |
| linux-realtime-6.14 | — | 6.14.0-1017.17~24.04.1 |
| linux-realtime-6.8 | — | 6.8.1-1041.42~22.04.1 |
| linux-riscv | — | — |
| linux-riscv-5.11 | — | — |
| linux-riscv-5.19 | — | — |
| linux-riscv-5.8 | — | — |
| linux-riscv-6.14 | — | 6.14.0-37.37.1~24.04.1 |
| linux-riscv-6.5 | — | — |
| linux-riscv-6.8 | — | 6.8.0-100.100~22.04.1 |
| linux-starfive-5.19 | — | — |
| linux-starfive-6.2 | — | — |
| linux-starfive-6.5 | — | — |
| linux-xilinx | — | 6.8.0-1023.24 |
References
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Exploit Protection
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