{"id":"DEBIAN-CVE-2021-4439","details":"In the Linux kernel, the following vulnerability has been resolved:  isdn: cpai: check ctr-\u003ecnr to avoid array index out of bound  The cmtp_add_connection() would add a cmtp session to a controller and run a kernel thread to process cmtp.  \t__module_get(THIS_MODULE); \tsession-\u003etask = kthread_run(cmtp_session, session, \"kcmtpd_ctr_%d\", \t\t\t\t\t\t\t\tsession-\u003enum);  During this process, the kernel thread would call detach_capi_ctr() to detach a register controller. if the controller was not attached yet, detach_capi_ctr() would trigger an array-index-out-bounds bug.  [   46.866069][ T6479] UBSAN: array-index-out-of-bounds in drivers/isdn/capi/kcapi.c:483:21 [   46.867196][ T6479] index -1 is out of range for type 'capi_ctr *[32]' [   46.867982][ T6479] CPU: 1 PID: 6479 Comm: kcmtpd_ctr_0 Not tainted 5.15.0-rc2+ #8 [   46.869002][ T6479] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 [   46.870107][ T6479] Call Trace: [   46.870473][ T6479]  dump_stack_lvl+0x57/0x7d [   46.870974][ T6479]  ubsan_epilogue+0x5/0x40 [   46.871458][ T6479]  __ubsan_handle_out_of_bounds.cold+0x43/0x48 [   46.872135][ T6479]  detach_capi_ctr+0x64/0xc0 [   46.872639][ T6479]  cmtp_session+0x5c8/0x5d0 [   46.873131][ T6479]  ? __init_waitqueue_head+0x60/0x60 [   46.873712][ T6479]  ? cmtp_add_msgpart+0x120/0x120 [   46.874256][ T6479]  kthread+0x147/0x170 [   46.874709][ T6479]  ? set_kthread_struct+0x40/0x40 [   46.875248][ T6479]  ret_from_fork+0x1f/0x30 [   46.875773][ T6479]","modified":"2026-09-15T09:02:30.060245398Z","published":"2024-06-20T12:15:10.447Z","upstream":["CVE-2021-4439"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2021-4439"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.14.16-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2021-4439.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.14.16-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2021-4439.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.14.16-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2021-4439.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}