# CVE-2025-39849: Linux Kernel out-of-bounds write in cfg80211 SME SSID handling

Source: https://junglewise.ai/threats/cve-2025-39849-linux-kernel-out-of-bounds-write-in-cfg80211-sme-ssid-handling  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2025-09-19. Updated: 2026-07-30  
License: CC BY 4.0 with a link back

CVE-2025-39849 · Severity: high · CVSS 8.8 · Published 2025-09-19

A vulnerability exists in the Linux kernel's wireless networking component that could lead to memory corruption when connecting to a Wi-Fi network. If a device connects to a malicious or malformed wireless access point providing an oversized network name (SSID), the system's memory could be compromised. This could result in a complete system crash or allow an attacker within wireless range to gain unauthorized control over the affected device.

Technologies: [Linux Kernel](https://junglewise.ai/threats/technologies/kernel), [Siemens SIMATIC CN 4100](https://junglewise.ai/threats/technologies/simatic-cn-4100). Vendors: [Linux](https://junglewise.ai/threats/vendors/linux), [Siemens](https://junglewise.ai/threats/vendors/siemens).

## Quick answers

**Is CVE-2025-39849 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-39849 being exploited in the wild.

**How severe is CVE-2025-39849?** High severity, with a CVSS score of 8.8, published 19 September 2025.

**Which products and versions are affected?** Linux Kernel 6.1.16 to 6.1.151, 6.2.3 to 6.3, 6.3 and later versions prior to 6.6.105, 6.12.46, 6.16.6, 6.1.16 to 6.1.151, 6.2.3 to 6.6.105, 6.7 to 6.12.46, 6.13 to 6.16.6; Siemens SIMATIC CN 4100 versions prior to V5.0.

**Is there a fix for CVE-2025-39849?** A patch was published on 2025-08-29: Initial patch authored by Dan Carpenter Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2025-39849 attacked?** It is attacked from the adjacent network, in an operating system.

**Am I affected by CVE-2025-39849?** Check whether you run Linux Kernel or Siemens SIMATIC CN 4100 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An out-of-bounds write vulnerability (CWE-787) exists in the Linux kernel's wireless configuration interface (cfg80211) within the Station Management Entity (SME) implementation. The function `__cfg80211_connect_result()` fails to validate that the SSID length provided in a connection result is within the standard `IEEE80211_MAX_SSID_LEN` (32 bytes) before performing a `memcpy` into the `wdev->u.client.ssid` buffer. An attacker within radio range (adjacent network) could broadcast a malformed SSID exceeding 32 bytes to trigger memory corruption. This can lead to a denial of service (kernel panic) or potential arbitrary code execution. The issue has been patched in multiple stable kernel branches including 6.1.151, 6.6.105, 6.12.46, and 6.16.6.

## Affected products

- Linux Linux Kernel 6.1.16 to 6.1.151, 6.2.3 to 6.3, 6.3 and later versions prior to 6.6.105, 6.12.46, 6.16.6
- Siemens SIMATIC CN 4100 versions prior to V5.0

## Timeline

- 2025-08-29: patched: Initial patch authored by Dan Carpenter
- 2025-09-19: disclosed: CVE published to NVD

## References

- [https://git.kernel.org/stable/c/31229145e6ba5ace3e9391113376fa05b7831ede](https://git.kernel.org/stable/c/31229145e6ba5ace3e9391113376fa05b7831ede)
- [https://git.kernel.org/stable/c/5cb7cab7adf9b1e6a99e2081b0e30e9e59d07523](https://git.kernel.org/stable/c/5cb7cab7adf9b1e6a99e2081b0e30e9e59d07523)
- [https://git.kernel.org/stable/c/62b635dcd69c4fde7ce1de4992d71420a37e51e3](https://git.kernel.org/stable/c/62b635dcd69c4fde7ce1de4992d71420a37e51e3)
- [https://git.kernel.org/stable/c/8e751d46336205abc259ed3990e850a9843fb649](https://git.kernel.org/stable/c/8e751d46336205abc259ed3990e850a9843fb649)
- [https://git.kernel.org/stable/c/e472f59d02c82b511bc43a3f96d62ed08bf4537f](https://git.kernel.org/stable/c/e472f59d02c82b511bc43a3f96d62ed08bf4537f)
- [https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html](https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html)
- [https://cert-portal.siemens.com/productcert/html/ssa-032379.html](https://cert-portal.siemens.com/productcert/html/ssa-032379.html)

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