{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-12235","assignerOrgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","state":"PUBLISHED","assignerShortName":"zephyr","dateReserved":"2026-06-15T01:56:05.689Z","datePublished":"2026-08-12T04:55:15.620Z","dateUpdated":"2026-08-12T12:34:55.518Z"},"containers":{"cna":{"providerMetadata":{"orgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","shortName":"zephyr","dateUpdated":"2026-08-12T04:55:15.620Z"},"title":"Out-of-bounds write in Xtensa llext PLT relocation from malformed ELF (CWE-787)","descriptions":[{"lang":"en","value":"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().\n\nrela.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.\n\nThe 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.\n\nThe fix adds a bound check rejecting any RELA entry whose r_offset >= tgt->sh_size, mirroring the existing validation in the shared branch."}],"affected":[{"vendor":"zephyrproject","product":"zephyr","collectionURL":"https://github.com/zephyrproject-rtos/zephyr","packageName":"zephyr","defaultStatus":"unaffected","programFiles":["subsys/llext/llext_link.c"],"versions":[{"version":"3.7.0","status":"affected","versionType":"semver","lessThan":"4.4.2"}]}],"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/106540afbd22087ad40b90f53fb22657754a719e","name":"Fix commit","tags":["patch"]},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-xv9q-6mrf-8j49","name":"GHSA-xv9q-6mrf-8j49"}],"metrics":[{"format":"CVSS","cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H","baseScore":6.3,"baseSeverity":"MEDIUM"}}],"problemTypes":[{"descriptions":[{"lang":"en","description":"bounds","cweId":"CWE-787","type":"CWE"}]}],"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-xv9q-6mrf-8j49","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-12T12:34:31.991332Z","id":"CVE-2026-12235","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-08-12T12:34:55.518Z"}}]}}