Linux Kernel up to 6.6.140/6.12.90/6.18.32/7.0.9 ppp_generic.c slhc_init null pointer dereference

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5.0$0-$5k0.00

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.6.140/6.12.90/6.18.32/7.0.9 and classified as critical. Affected by this issue is the function slhc_init of the file ppp_generic.c. The manipulation results in null pointer dereference. This vulnerability was named CVE-2026-45842. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical has been found in Linux Kernel up to 6.6.140/6.12.90/6.18.32/7.0.9. Affected is the function slhc_init of the file ppp_generic.c. The manipulation with an unknown input leads to a null pointer dereference vulnerability. CWE is classifying the issue as CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. This is going to have an impact on availability. CVE summarizes:

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.

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2026-45842 since 05/13/2026. The exploitability is told to be difficult. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 321588 (SUSE SLES16 Security Update : kernel (SUSE-SU-2026:22127-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.141, 6.12.91, 6.18.33, 7.0.10 or 7.1-rc1 eliminates this vulnerability. Applying the patch c6980e8b1a86288167f34966fa5219031999b6f1/de42f86e2cf5028a97e74c25869d1a962b13c301/9e1ff0eead073c4f46d874ad2526b7dda5465faf/7b0d9e878ec2b21d99ae8051b3dda59cdb66c152/e76607442d5b73e1ba6768f501ef815bb58c2c0e is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (321588), EUVD (EUVD-2026-32168) and CERT Bund (WID-SEC-2026-1691). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

  • SUSE Linux
  • SUSE openSUSE
  • Open Source Linux Kernel

Productinfo

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Version

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Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.1
VulDB Meta Temp Score: 5.0

VulDB Base Score: 4.8
VulDB Temp Score: 4.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Null pointer dereference
CWE: CWE-476 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 321588
Nessus Name: SUSE SLES16 Security Update : kernel (SUSE-SU-2026:22127-1)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.6.141/6.12.91/6.18.33/7.0.10/7.1-rc1
Patch: c6980e8b1a86288167f34966fa5219031999b6f1/de42f86e2cf5028a97e74c25869d1a962b13c301/9e1ff0eead073c4f46d874ad2526b7dda5465faf/7b0d9e878ec2b21d99ae8051b3dda59cdb66c152/e76607442d5b73e1ba6768f501ef815bb58c2c0e

Timelineinfo

05/13/2026 CVE reserved
05/27/2026 +14 days Advisory disclosed
05/27/2026 +0 days VulDB entry created
06/26/2026 +30 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-45842 (🔒)
GCVE (CVE): GCVE-0-2026-45842
GCVE (VulDB): GCVE-100-366048
EUVD: 🔒
CERT Bund: WID-SEC-2026-1691 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 05/27/2026 13:45
Updated: 06/26/2026 21:05
Changes: 05/27/2026 13:45 (59), 05/27/2026 16:01 (1), 05/27/2026 20:35 (7), 06/15/2026 12:29 (1), 06/20/2026 21:47 (2), 06/26/2026 21:05 (12)
Complete: 🔍
Cache ID: 216::103

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