{"answers":{"affected":"","exploited":"There is no known exploitation of CVE-2026-79976 in the wild and no public exploit code.","fix":"No fix has been published for CVE-2026-79976 yet. Limit exposure of the affected software until one is available.","what":"CVE-2026-79976 is a high-severity vulnerability in zephyrproject zephyr, published on 21 Oct 2026."},"fix_prompt":"Check this codebase for CVE-2026-79976 and fix it if it is affected.\n\nWhat it is: CVE-2026-79976 is a high-severity vulnerability in zephyrproject zephyr, published on 21 Oct 2026. \nExploitation: There is no known exploitation of CVE-2026-79976 in the wild and no public exploit code.\n\nAffected product: zephyrproject zephyr. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-79976/ (Markdown: https://insights.sbomify.com/CVE-2026-79976/index.md)","id":"CVE-2026-79976","markdown":"https://insights.sbomify.com/CVE-2026-79976/index.md","name":"CVE-2026-79976","record":{"aliases":["GHSA-76fx-m4mf-24gq"],"analysis":null,"analysis_generated_by":null,"assigner":"zephyr","cpe":[],"cvss":{"score":7.1,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H","version":"3.1"},"cwes":[{"id":"CWE-476","name":"NULL Pointer Dereference"}],"description":"The MCTP-over-I2C+GPIO target binding in subsys/pmci/mctp/mctp_i2c_gpio_target.c emulates a small pseudo-register file, where the bus controller first writes a register number and then writes or reads payload bytes. The selected register (b-\u003ereg_addr) and the data-phase flag (b-\u003erxtx) were never cleared when the controller issued an I2C STOP, so after a completed transfer the target still had a data register selected while the packet buffer that register refers to had already been consumed and set to NULL by mctp_i2c_gpio_target_stop().\n\nA controller on the bus can re-enter the same branch of mctp_i2c_gpio_target_stop() with a NULL buffer using two ordinary transactions and no authentication: first a normal packet write to MCTP_I2C_GPIO_RX_MSG_ADDR followed by STOP (which delivers and frees b-\u003erx_pkt), then a bare read transaction followed by STOP. The failing read_requested() call leaves the stale state untouched and the I2C driver still delivers the STOP callback, which then calls mctp_bus_rx() with a NULL packet. The symmetric case exists on the transmit side, where the stale MCTP_I2C_GPIO_TX_MSG_ADDR selection dereferences b-\u003etx_pkt-\u003eend after b-\u003etx_pkt has been cleared and additionally signals b-\u003etx_complete a second time, causing the next outbound packet to be dropped.\n\nThe dereference happens in the I2C target interrupt handler, so on any target that traps accesses to address 0 the result is a fatal exception and a device reset or halt — a denial of service inflicted by any device able to act as controller on the shared management bus (for example compromised firmware on a peer MCTP endpoint or on the BMC). On parts where address 0 is readable, the impact degrades to a malformed packet buffer being handed to the MCTP stack and lost transmit packets. No attacker-controlled value is written and no confidentiality or integrity boundary is crossed.\n\nThe fix resets b-\u003ereg_addr to MCTP_I2C_GPIO_INVALID_ADDR and clears b-\u003erxtx at every STOP, so a new register must be selected before any data phase can run again. Only builds that opt into the experimental CONFIG_MCTP subsystem with CONFIG_MCTP_I2C_GPIO_TARGET=y are affected.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":false,"headline":"NULL pointer dereference in the MCTP I2C+GPIO target binding triggerable by a peer I2C controller","id":"CVE-2026-79976","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":null,"year":"2026"},"n_packages":0,"n_references":2,"next":{"headline":"WireGuard peer endpoint learned from unauthenticated transport-data messages allows off-path tunnel hijack in Zephyr","id":"CVE-2026-79977"},"packages":[],"prev":{"headline":"Server-side request forgery in Secure Connect Gateway 5.0 - Appliance","id":"CVE-2026-79975"},"products":["zephyr"],"published":"2026-10-21","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-10-23","vendors":["zephyrproject"]},"summary":null,"url":"https://insights.sbomify.com/CVE-2026-79976/"}