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CVE-2026-12235: bounds in zephyrproject zephyr

0
Medium
VulnerabilityCVE-2026-12235cvecve-2026-12235
Published: 08/12/2026 (08/12/2026, 04:55:15 UTC)
Source: CVE Database V5
Vendor/Project: zephyrproject
Product: zephyr

Description

The Linkable Loadable Extensions (llext) subsystem mis-handles PLT/RELA relocation entries when linking a relocatable (partially-linked) ELF extension. In llext_link_plt() (subsys/llext/llext_link.c), the relocatable branch (tgt != NULL, the path used for Xtensa relocatable objects) computed the patch address as ext->mem[LLEXT_MEM_TEXT] - text.sh_offset + rela.r_offset + tgt->sh_offset and then performed the relocation write there without validating rela.r_offset. Its sibling shared/dynamic branch already rejected out-of-range offsets via llext_file_offset(). rela.r_offset is read directly from the ELF's RELA table, so a crafted entry with an offset larger than the target section makes the write land arbitrarily far outside the extension's text buffer. The result is an attacker-influenced out-of-bounds write (the location via r_offset, the written value being the resolved symbol address) performed in supervisor context at link time, before any extension code runs. The path is reached from llext_load() whenever an application loads an attacker-influenced ELF extension on Xtensa with writable storage; llext is documented to accept extensions of untrusted origin. Impact is supervisor-context memory corruption (integrity and availability loss, and a sandbox-boundary escape for user-mode extensions). Exploitation is gated by the Xtensa relocatable PLT path and writable storage, and turning the out-of-range write into a useful primitive is non-trivial. The fix adds a bound check rejecting any RELA entry whose r_offset >= tgt->sh_size, mirroring the existing validation in the shared branch.

CVSS v3.1

Score 6.3medium

Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
High
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H

Affected software

GitHub Actionsmore threats →cve
zephyr
pkg:github/zephyr
Affected versions
>=3.7.0 <4.4.2

Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.

Technical Details

Data Version
5.2
Assigner Short Name
zephyr
Date Reserved
2026-06-15T01:56:05.689Z
Cvss Version
3.1
State
PUBLISHED
Remediation Level
null

Threat ID: 6a7c6c5abf8831d5398f6fb6

Added to database: 08/12/2026, 12:51:38 UTC

Last updated: 08/12/2026, 12:51:38 UTC

Views: 1

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