CVE-2025-39686comedi: Make insn_rw_emulate_bits() do insn->n samples
Updated under an hour ago ()
Does this affect you?
It affects Linux and 3 other products. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
Do this next
Free account, 1 product
In the Linux kernel, the following vulnerability has been resolved: comedi: Make insn_rw_emulate_bits() do insn->n samples The `insn_rw_emulate_bits()` function is used as a default handler for `INSN_READ` instructions for subdevices that have a handler for `INSN_BITS` but not for `INSN_READ`. Similarly, it is used as a default handler for `INSN_WRITE` instructions for subdevices that have a handler for `INSN_BITS` but not for `INSN_WRITE`. It works by emulating the `INSN_READ` or `INSN_WRITE` instruction handling with a constructed `INSN_BITS` instruction. However, `INSN_READ` and `INSN_WRITE` instructions are supposed to be able read or write multiple samples, indicated by the `insn->n` value, but `insn_rw_emulate_bits()` currently only handles a single sample. For `INSN_READ`, the comedi core will copy `insn->n` samples back to user-space. (That triggered KASAN kernel-infoleak errors when `insn->n` was greater than 1, but that is being fixed more generally elsewhere in the comedi core.) Make `insn_rw_emulate_bits()` either handle `insn->n` samples, or return an error, to conform to the general expectation for `INSN_READ` and `INSN_WRITE` handlers.
- CVSS
- 7.8 HIGH (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Modified
- Record last updated
- May 12, 2026
- First seen by InfoSec Signals
- Oct 19, 2026
Affected products
Linux Linux linux:linux (from the name) | from ed9eccbe8970f6eedc1b978c157caf1251a896d4 before ab77e85bd3bc006ef40738f26f446a660813da44; from ed9eccbe8970f6eedc1b978c157caf1251a896d4 before ae8bc1f07bcb31b8636420e03d1f9c3df6219a2b; from ed9eccbe8970f6eedc1b978c157caf1251a896d4 before 842f307a1d115b24f2bcb2415c4e344f11f55930; from ed9eccbe8970f6eedc1b978c157caf1251a896d4 before 92352ed2f9ac422181e381c2430c2d0dfb46faa0; from ed9eccbe8970f6eedc1b978c157caf1251a896d4 before dc0a2f142d655700db43de90cb6abf141b73d908; from ed9eccbe8970f6eedc1b978c157caf1251a896d4 before 7afba9221f70d4cbce0f417c558879cba0eb5e66 | CNA record |
Siemens SIMATIC CN 4100 siemens:simatic_cn_4100 (from the name) | before V5.0 | CISA ADP |
linux linux_kernel linux:linux_kernel | from 2.6.29 before 5.15.190; from 5.16 before 6.1.149; from 6.2 before 6.6.103; from 6.7 before 6.12.44; from 6.13 before 6.16.4; 6.17; 6.17 | NVD |
debian debian_linux debian:debian_linux | 11.0 | NVD |
References
- https://git.kernel.org/stable/c/ab77e85bd3bc006ef40738f26f446a660813da44patch
- https://git.kernel.org/stable/c/ae8bc1f07bcb31b8636420e03d1f9c3df6219a2bpatch
- https://git.kernel.org/stable/c/842f307a1d115b24f2bcb2415c4e344f11f55930patch
- https://git.kernel.org/stable/c/92352ed2f9ac422181e381c2430c2d0dfb46faa0patch
- https://git.kernel.org/stable/c/dc0a2f142d655700db43de90cb6abf141b73d908patch
- https://git.kernel.org/stable/c/7afba9221f70d4cbce0f417c558879cba0eb5e66patch
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.htmlmailing-list, third-party-advisory
- https://cert-portal.siemens.com/productcert/html/ssa-032379.html
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.