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CVE-2026-99121

UnknownEPSS 0.17%

Last modified

CVE-2026-99121 is a vulnerability of currently unknown severity. In the Linux kernel, the following vulnerability has been resolved: ipv4: avoid divide by zero in fib_rebalance fib_rebalance() computes the total eligible nexthop weight in one pass and programs upper bounds in a second pass. A concurrent change to ignore_routes_with_linkdown can make the first pass return zero while the second pass sees an eligible nexthop, resulting in division by zero. If the first pass reports a zero total, set each nexthop upper bound to -1 and skip the division. EPSS estimates a 0.17% chance of exploitation in the next 30 days.

Description

In the Linux kernel, the following vulnerability has been resolved: ipv4: avoid divide by zero in fib_rebalance fib_rebalance() computes the total eligible nexthop weight in one pass and programs upper bounds in a second pass. A concurrent change to ignore_routes_with_linkdown can make the first pass return zero while the second pass sees an eligible nexthop, resulting in division by zero. If the first pass reports a zero total, set each nexthop upper bound to -1 and skip the division. This matches the IPv6 fix in commit d2c26c2911dd ("ipv6: avoid divide by zero in rt6_multipath_rebalance") and preserves the lock-free rebalance path.

Metrics

EPSS Probability
0.17%

6.9th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= 0e884c78ee19e902f300ed147083c28a0c6302f0, < baf3a767b2845eb8e68f056ee4aa5b41b151e990; >= 0e884c78ee19e902f300ed147083c28a0c6302f0, < f655a26490e705ec76a79db7f412847fda342b39; >= 0e884c78ee19e902f300ed147083c28a0c6302f0, < 7c68f4de5090b17b63b9a0a3b01b3807e01a296a; >= 0e884c78ee19e902f300ed147083c28a0c6302f0, < 226a974054acbd892560bfa67f0ae8ffe271a736; >= 0e884c78ee19e902f300ed147083c28a0c6302f0, < 0800c92ca5d1983df6843a5435299978901d1d02; >= 0e884c78ee19e902f300ed147083c28a0c6302f0, < 5dac5c7ba8f5f3fb4bf29f2a2c3cb552f5b83c8f; >= 0e884c78ee19e902f300ed147083c28a0c6302f0, < d5520e815c4b1427104ce1428ee23821f2aa824d; >= 0e884c78ee19e902f300ed147083c28a0c6302f0, < 5046d2880fec7d49ebed2fd2866747ee1d06ad71
LinuxLinux4.4

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-99121?
In the Linux kernel, the following vulnerability has been resolved: ipv4: avoid divide by zero in fib_rebalance fib_rebalance() computes the total eligible nexthop weight in one pass and programs upper bounds in a second pass. A concurrent change to ignore_routes_with_linkdown can make the first pass return zero while the second pass sees an eligible nexthop, resulting in division by zero. If the first pass reports a zero total, set each nexthop upper bound to -1 and skip the division. This matches the IPv6 fix in commit d2c26c2911dd ("ipv6: avoid divide by zero in rt6_multipath_rebalance") and preserves the lock-free rebalance path.
How severe is CVE-2026-99121?
Severity scoring for CVE-2026-99121 is pending analysis. The EPSS model estimates a 0.17% probability of exploitation in the next 30 days.
How do I fix CVE-2026-99121?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST