--- id: CVE-2026-45842 title: |- In the Linux kernel, the following vulnerability has been resolved: slip: reject VJ receive packets on instances with no rstate array slhc_init() accepts rslots == 0 as a valid configuration, with the documented meaning of 'no receive … summary: |- In the Linux kernel, the following vulnerability has been resolved: slip: reject VJ receive packets on instances with no rstate array slhc_init() accepts rslots == 0 as a valid configuration, with the documented meaning of 'no receive … severity: medium cvss: 5.5 cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H' cwe: - CWE-476 vendor: linux product: linux_kernel affected: - 'linux_kernel >= 2.6.32.70, < 2.6.33' - 'linux_kernel >= 3.2.75, < 3.3' - 'linux_kernel >= 3.4.111, < 3.5' - 'linux_kernel >= 3.10.96, < 3.11' - 'linux_kernel >= 3.12.53, < 3.13' - 'linux_kernel >= 3.14.60, < 3.15' - 'linux_kernel >= 3.18.27, < 3.19' - 'linux_kernel >= 4.1.17, < 4.2' - 'linux_kernel >= 4.3.5, < 5.10.258' - 'linux_kernel >= 5.11, < 5.15.209' - 'linux_kernel >= 5.16, < 6.1.175' - 'linux_kernel >= 6.2, < 6.6.141' - 'linux_kernel >= 6.7, < 6.12.91' - 'linux_kernel >= 6.13, < 6.18.33' - 'linux_kernel >= 6.19, < 7.0.10' patched: - linux_kernel 7.0.10 published: '2026-05-27' updated: '2026-10-15' sourceUpdated: '2026-10-15T02:19:37.047' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-45842' references: - url: 'https://git.kernel.org/stable/c/3d71c961febddd855d3ae9a519eeb96c8023f430' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/4aa9eca6fda2919027dfd7a7cc69334982d89586' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/72304fec672e8aac9ee7b9c475db96b37cca8d8d' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/7b0d9e878ec2b21d99ae8051b3dda59cdb66c152' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/9e1ff0eead073c4f46d874ad2526b7dda5465faf' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/c6980e8b1a86288167f34966fa5219031999b6f1' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/de42f86e2cf5028a97e74c25869d1a962b13c301' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/e76607442d5b73e1ba6768f501ef815bb58c2c0e' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://cert-portal.siemens.com/productcert/html/ssa-784472.html' label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e tags: - nvd - cve.org epss: 0.00162 epssPercentile: 0.0507 ingestedAt: '2026-10-15T03:30:12.878Z' --- ## Overview In the Linux kernel, the following vulnerability has been resolved: slip: reject VJ receive packets on instances with no rstate array slhc_init() accepts rslots == 0 as a valid configuration, with the documented meaning of 'no receive compression'. In that case the allocation loop in slhc_init() is skipped, so comp->rstate stays NULL and comp->rslot_limit stays 0 (from the kzalloc of struct slcompress). The receive helpers do not defend against that configuration. slhc_uncompress() dereferences comp->rstate[x] when the VJ header carries an explicit connection ID, and slhc_remember() later assigns cs = &comp->rstate[...] after only comparing the packet's slot number to comp->rslot_limit. Because rslot_limit is 0, slot 0 passes the range check, and the code dereferences a NULL rstate. The configuration is reachable in-tree through PPP. PPPIOCSMAXCID stores its argument in a signed int, and (val >> 16) uses arithmetic shift. Passing 0xffff0000 therefore sign-extends to -1, so val2 + 1 is 0 and ppp_generic.c ends up calling slhc_init(0, 1). Because /dev/ppp open is gated by ns_capable(CAP_NET_ADMIN), the whole path is reachable from an unprivileged user namespace. Once the malformed VJ state is installed, any inbound VJ-compressed or VJ-uncompressed frame that selects slot 0 crashes the kernel in softirq context: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: 0010:slhc_uncompress (drivers/net/slip/slhc.c:519) Call Trace: ppp_receive_nonmp_frame (drivers/net/ppp/ppp_generic.c:2466) ppp_input (drivers/net/ppp/ppp_generic.c:2359) ppp_async_process (drivers/net/ppp/ppp_async.c:492) tasklet_action_common (kernel/softirq.c:926) handle_softirqs (kernel/softirq.c:623) run_ksoftirqd (kernel/softirq.c:1055) smpboot_thread_fn (kernel/smpboot.c:160) kthread (kernel/kthread.c:436) ret_from_fork (arch/x86/kernel/process.c:164) Reject the receive side on such instances instead of touching rstate. slhc_uncompress() falls through to its existing 'bad' label, which bumps sls_i_error and enters the toss state. slhc_remember() mirrors that with an explicit sls_i_error increment followed by slhc_toss(); the sls_i_runt counter is not used here because a missing rstate is an internal configuration state, not a runt packet. The transmit path is unaffected: the only in-tree caller that picks rslots from userspace (ppp_generic.c) still supplies tslots >= 1, and slip.c always calls slhc_init(16, 16), so comp->tstate remains valid and slhc_compress() continues to work. ## Affected - `linux_kernel >= 2.6.32.70, < 2.6.33` - `linux_kernel >= 3.2.75, < 3.3` - `linux_kernel >= 3.4.111, < 3.5` - `linux_kernel >= 3.10.96, < 3.11` - `linux_kernel >= 3.12.53, < 3.13` - `linux_kernel >= 3.14.60, < 3.15` - `linux_kernel >= 3.18.27, < 3.19` - `linux_kernel >= 4.1.17, < 4.2` - `linux_kernel >= 4.3.5, < 5.10.258` - `linux_kernel >= 5.11, < 5.15.209` - `linux_kernel >= 5.16, < 6.1.175` - `linux_kernel >= 6.2, < 6.6.141` - `linux_kernel >= 6.7, < 6.12.91` - `linux_kernel >= 6.13, < 6.18.33` - `linux_kernel >= 6.19, < 7.0.10` ## Remediation Upgrade past the affected range: - `linux_kernel 7.0.10`