Out-of-bounds Write Affecting linux-6.12 package, versions <6.12.100-1~deb12u1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-ECHOLATEST-LINUX612-18579288
- published7 Aug 2026
- disclosed25 Jul 2026
Introduced: 25 Jul 2026
CVE-2026-64449 (opens in a new tab)How to fix?
Upgrade Echo:latest linux-6.12 to version 6.12.100-1~deb12u1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream linux-6.12 package and not the linux-6.12 package as distributed by Echo.
See How to fix? for Echo:latest relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
staging: vme_user: bound slave read/write to the kern_buf size
The SLAVE-path helpers buffer_to_user() and buffer_from_user() copy 'count' bytes into/out of the fixed-size kern_buf (size_buf == PCI_BUF_SIZE == 0x20000, 128 KiB) using *ppos as the offset, without bounding *ppos + count against size_buf.
vme_user_write()/vme_user_read() only clamp count to the VME window size (image_size = vme_get_size(resource)), which VME_SET_SLAVE sets from the user-supplied slave.size -- validated against the VME address space (up to VME_A32_MAX = 4 GiB), not against PCI_BUF_SIZE. When the window exceeds 128 KiB, a write()/read() copies past the kern_buf allocation.
Clamp count against size_buf in both helpers, with an early return when *ppos is already at/after the buffer end. *ppos is >= 0 here (the caller rejects negative offsets), so size_buf - *ppos cannot wrap. This mirrors the existing clamp in the MASTER-path helpers resource_to_user() / resource_from_user(), and matches the read()/write() convention of a short transfer at end-of-buffer.
Found by static analysis (CodeQL taint tracking + CBMC bounded model checking) and confirmed dynamically under KASAN with the vme_fake bridge:
BUG: KASAN: slab-out-of-bounds in _copy_from_user+0x2d/0x80 Write of size 262144 at addr ffff888004100000 by task trigger/68 _copy_from_user+0x2d/0x80 vme_user_write+0x13e/0x240 [vme_user] vfs_write+0x1b8/0x7a0 ksys_write+0xb8/0x150
References
- https://advisory.echohq.com/cve/CVE-2026-64449
- https://git.kernel.org/stable/c/1b495fa0d4927c88d88bf346bf311f2e26e860ed
- https://git.kernel.org/stable/c/65358d89dc9f1c25d9364b2b3ef0f3b47717f9ed
- https://git.kernel.org/stable/c/8eff7cd4817e14dbe3b9952cce55ef52d1d38940
- https://git.kernel.org/stable/c/9f32f38265014fac7f5dc9490fb01a638ce6e121
- https://git.kernel.org/stable/c/adc8b9c30d716c362646edb45662aa1c641a154a
- https://git.kernel.org/stable/c/e99f2df433c63c86c93de1e5f08f16e404388756