Linux Kernel up to 6.18.51/7.2.5 IPv6 net/ipv6/route.c rt6_upper_bound_set divide by zero

CVSS Meta Temp Score
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CTI Interest Score
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4.7$0-$5k0.86-

Summaryinfo

A vulnerability, which was classified as problematic, was found in Linux Kernel up to 6.18.51/7.2.5. This impacts the function rt6_upper_bound_set of the file net/ipv6/route.c of the component IPv6. Executing a manipulation can lead to divide by zero. This vulnerability appears as CVE-2026-89790. The attack may be performed from remote. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in Linux Kernel up to 6.18.51/7.2.5. This vulnerability affects the function rt6_upper_bound_set of the file net/ipv6/route.c of the component IPv6. The manipulation with an unknown input leads to a divide by zero vulnerability. The CWE definition for the vulnerability is CWE-369. The product divides a value by zero. As an impact it is known to affect availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: ipv6: avoid divide by zero in rt6_multipath_rebalance rt6_multipath_rebalance() calculates the total eligible nexthop weight in one pass and programs upper bounds in a second pass. Since RTM_NEWROUTE is RTNL-free, a concurrent ignore_routes_with_linkdown update can make the first pass return zero while the second sees an eligible nexthop, causing rt6_upper_bound_set() to divide by zero. UBSAN: division-overflow in net/ipv6/route.c:4845:17 Oops: divide error: 0000 [#1] SMP KASAN NOPTI rt6_upper_bound_set() net/ipv6/route.c:4845 rt6_multipath_rebalance() fib6_add_rt2node() ip6_route_multipath_add() inet6_rtm_newroute() Skip upper-bound calculation when the first pass reports a zero total. This respects the lock-free performance considerations here and solves insecure scenarios.

The advisory is shared for download at git.kernel.org. This vulnerability was named CVE-2026-89790 since 09/11/2026. The exploitation appears to be easy. The attack can be initiated remotely. Additional levels of successful authentication are necessary for exploitation. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 6.18.52, 7.2.6 or 7.3-rc1 eliminates this vulnerability. Applying the patch f30cf8fd9872299c0c27f9916252ba2b9f422dce/f82b5dbb2fef65b52a62d5ffe05e0483c4385a83/d2c26c2911dd1a363c488add4fb63eb5f0f28f87 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-80311). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.9
VulDB Meta Temp Score: 4.7

VulDB Base Score: 4.9
VulDB Temp Score: 4.7
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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

Exploitinginfo

Class: Divide by zero
CWE: CWE-369 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.18.52/7.2.6/7.3-rc1
Patch: f30cf8fd9872299c0c27f9916252ba2b9f422dce/f82b5dbb2fef65b52a62d5ffe05e0483c4385a83/d2c26c2911dd1a363c488add4fb63eb5f0f28f87

Timelineinfo

09/11/2026 CVE reserved
09/16/2026 +5 days Advisory disclosed
09/16/2026 +0 days VulDB entry created
09/16/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-89790 (🔒)
GCVE (CVE): GCVE-0-2026-89790
GCVE (VulDB): GCVE-100-405568
EUVD: 🔒

Entryinfo

Created: 09/16/2026 11:06
Updated: 09/16/2026 12:15
Changes: 09/16/2026 11:06 (60), 09/16/2026 12:15 (1)
Complete: 🔍
Cache ID: 216::103

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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