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
Affected Vendors & Products
| Vendors | Products |
|---|---|
| Linux |
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No data.
References
History
Wed, 28 Oct 2026 13:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-369 |
Wed, 28 Oct 2026 12:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Linux linux
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| Vendors & Products |
Linux linux
|
Wed, 28 Oct 2026 10:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | ipv4: avoid divide by zero in fib_rebalance | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published: 2026-10-28T10:34:37.082Z
Updated: 2026-10-28T10:34:37.082Z
Reserved: 2026-09-25T10:25:14.393Z
Link: CVE-2026-99121
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-10-28T11:17:31.733
Modified: 2026-10-28T11:17:31.733
Link: CVE-2026-99121
Redhat
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