CVE-2026-112112

An IPv6 FlowSpec validation bypass in the CZ.NIC BIRD Internet Routing Daemon allows an established BGP peer to inject FlowSpec rules matching destinations outside the address space authorized by the unicast-route validation procedure. With validation enabled on the receiving flow6 channel, BIRD fails to reject a destination prefix component with a nonzero offset, contrary to RFC 8956 section 5. It validates a reconstructed prefix with zero-filled skipped bits, although the original FlowSpec component can match a broader set of IPv6 addresses. Given a suitable unicast route from the peer, the rule can pass validation and, where export policy permits, be propagated to downstream peers. Downstream enforcement may cause unauthorized traffic filtering or redirection.

CVSS

No CVSS.

References

Link	Resource
https://gitlab.nic.cz/labs/bird/-/blob/v2.20.0/nest/rt-table.c#L2686
https://gitlab.nic.cz/labs/bird/-/blob/v3.4.0/nest/rt-table.c#L4518
https://gitlab.nic.cz/labs/bird/-/commit/7cf75587b6f38b87849fe192bf5dfd124b7702bc
https://www.rfc-editor.org/rfc/rfc8956.html#section-5

Configurations

No configuration.

History

18 Oct 2026, 23:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-18 23:16

Updated : 2026-10-19 21:14

NVD link : CVE-2026-112112

Mitre link : CVE-2026-112112

CVE.ORG link : CVE-2026-112112

JSON object : View

Products Affected

No product.

CWE

CWE-1284

Improper Validation of Specified Quantity in Input

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