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Improper Validation of Specified Quantity in Input Affecting bird2 package, versions *

Severity

 Recommended
low

Based on Debian security rating.

Threat Intelligence

EPSS
0.31% (24th percentile)

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  • Snyk IDSNYK-DEBIAN13-BIRD2-21246260
  • published19 Oct 2026
  • disclosed18 Oct 2026
Report a new vulnerability Found a mistake?

Introduced: 18 Oct 2026

NewCVE-2026-112112  (opens in a new tab)
CWE-1284  (opens in a new tab)

How to fix?

There is no fixed version for Debian:13 bird2.

NVD Description

Note: Versions mentioned in the description apply only to the upstream bird2 package and not the bird2 package as distributed by Debian. See How to fix? for Debian:13 relevant fixed versions and status.

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.