Loop with Unreachable Exit Condition ('Infinite Loop') Affecting bpftool6.12-debuginfo package, versions <1:6.12.94-123.174.amzn2023


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.17% (7th percentile)

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  • Snyk IDSNYK-AMZN2023-BPFTOOL612DEBUGINFO-18529339
  • published5 Aug 2026
  • disclosed19 Jul 2026

Introduced: 19 Jul 2026

NewCVE-2026-63983  (opens in a new tab)
CWE-835  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 bpftool6.12-debuginfo to version 1:6.12.94-123.174.amzn2023 or higher.
This issue was patched in ALAS2023-2026-1968.

NVD Description

Note: Versions mentioned in the description apply only to the upstream bpftool6.12-debuginfo package and not the bpftool6.12-debuginfo package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

net/sched: fix packet loop on netem when duplicate is on

When netem duplicates a packet it re-enqueues the copy at the root qdisc. If another netem sits in the tree the copy can be duplicated again, recursing until the stack or memory is exhausted.

The original duplication guard temporarily zeroed q->duplicate around the re-enqueue, but that does not cover all cases because it is per-qdisc state shared across all concurrent enqueue paths and is not safe without additional locking.

Use the skb tc_depth field introduced in an earlier patch:

  • increment it on the duplicate before re-enqueue
  • skip duplication for any skb whose tc_depth is already non-zero.

This marks the packet itself rather than mutating qdisc state, therefore it is safe regardless of tree topology or concurrency.

CVSS Base Scores

version 3.1