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CVE-2026-45842

Vulnérabilité non évaluée dans Linux (Linux)

CVSS 0.0 · Non évaluée
EPSS 0.2%
Linux•Linux•Versions : <=6.1.*, <=7.0.*, <3d71c961febddd855d3ae9a519eeb96c8023f430, <=6.12.*, <4.2, <e76607442d5b73e1ba6768f501ef815bb58c2c0e, <3.15, a1c3860d3c5fc62bd35f089bcb03f18a37242de9, <7b0d9e878ec2b21d99ae8051b3dda59cdb66c152, <3.13, 3.4.111, <72304fec672e8aac9ee7b9c475db96b37cca8d8d, <c6980e8b1a86288167f34966fa5219031999b6f1, <3.11, 0, <4aa9eca6fda2919027dfd7a7cc69334982d89586, 2.6.32.70, 354b254af5c1350de9586af75fe5a821b35bfb33, 6.18.33, <3.3, 4.3.5, 4.4, 3.2.75, 5.15.209, 6.12.91, <de42f86e2cf5028a97e74c25869d1a962b13c301, <=5.10.*, <=6.6.*, 6.1.175, 6b4fa561e26526c62636414d267342c945084f44, 4.1.17, 3.18.27, df085f1cb3acd3d75408ff94f366983873bce7d2, 6.6.141, <2.6.33, <3.5, 3.10.96, 3.14.60, <=6.18.*, 7.1, 5148857f5d4c812cc918cf4627f7880521e987eb, 7.0.10, 82185755d90c8047c6f4b589c39998ff3d4ca3ad, 5.10.258, <9e1ff0eead073c4f46d874ad2526b7dda5465faf, <=*, 4ab42d78e37a294ac7bc56901d563c642e03c4ae, <=5.15.*, f82699de104eaf8a7ffc2849a566a94818dd8a3c, <3.19, 42fc512469e78939c1e419d3310c47de55bdcbb8, 3.12.53, a50a93cc99286dc444c7e5ccc7dfb9d58c2d346d, <4.4

Description

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: <TASK> 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) </TASK> 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.

Gravité et risque d'exploitation

CVE-2026-45842 obtient un score CVSS de 0.0/10, soit une gravité non évaluée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.17 %, ce qui la place devant 5.5 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <=6.1.*, <=7.0.*, <3d71c961febddd855d3ae9a519eeb96c8023f430, <=6.12.*, <4.2, <e76607442d5b73e1ba6768f501ef815bb58c2c0e, <3.15, a1c3860d3c5fc62bd35f089bcb03f18a37242de9, <7b0d9e878ec2b21d99ae8051b3dda59cdb66c152, <3.13, 3.4.111, <72304fec672e8aac9ee7b9c475db96b37cca8d8d, <c6980e8b1a86288167f34966fa5219031999b6f1, <3.11, 0, <4aa9eca6fda2919027dfd7a7cc69334982d89586, 2.6.32.70, 354b254af5c1350de9586af75fe5a821b35bfb33, 6.18.33, <3.3, 4.3.5, 4.4, 3.2.75, 5.15.209, 6.12.91, <de42f86e2cf5028a97e74c25869d1a962b13c301, <=5.10.*, <=6.6.*, 6.1.175, 6b4fa561e26526c62636414d267342c945084f44, 4.1.17, 3.18.27, df085f1cb3acd3d75408ff94f366983873bce7d2, 6.6.141, <2.6.33, <3.5, 3.10.96, 3.14.60, <=6.18.*, 7.1, 5148857f5d4c812cc918cf4627f7880521e987eb, 7.0.10, 82185755d90c8047c6f4b589c39998ff3d4ca3ad, 5.10.258, <9e1ff0eead073c4f46d874ad2526b7dda5465faf, <=*, 4ab42d78e37a294ac7bc56901d563c642e03c4ae, <=5.15.*, f82699de104eaf8a7ffc2849a566a94818dd8a3c, <3.19, 42fc512469e78939c1e419d3310c47de55bdcbb8, 3.12.53, a50a93cc99286dc444c7e5ccc7dfb9d58c2d346d, <4.4) est présent sur votre parc.
  • Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
  • À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
  • Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

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