Reachable Assertion Affecting bpftool6.18-debuginfo package, versions <1:6.18.54-121.166.amzn2023
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-AMZN2023-BPFTOOL618DEBUGINFO-21417118
- published22 Oct 2026
- disclosed25 Sept 2026
Introduced: 25 Sep 2026
NewCVE-2026-98044 (opens in a new tab)How to fix?
Upgrade Amazon-Linux:2023 bpftool6.18-debuginfo to version 1:6.18.54-121.166.amzn2023 or higher.
This issue was patched in ALAS2023-2026-3192.
NVD Description
Note: Versions mentioned in the description apply only to the upstream bpftool6.18-debuginfo package and not the bpftool6.18-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:
bpf: Reject legacy packet loads from callbacks
check_ld_abs() models a failed BPF_LD_ABS or BPF_LD_IND in a subprogram as an implicit return with R0 set to zero. It calls prepare_func_exit() to explore this synthesized path.
When the load is reached directly from a synchronous callback, prepare_func_exit() enforces the callback return contract and marks R0 precise. R0 is not derived from a real instruction on this path, so precision backtracking reaches the callback call with R0 still requested and triggers the "callback unexpected regs" verifier bug. A privileged program loader can therefore cause a verifier warning and an -EFAULT BPF_PROG_LOAD.
These legacy packet-load instructions are deprecated. Reject them from callbacks rather than complicating their implicit-return model. Check all active frames before constructing the implicit return so nested static subprograms cannot hide the callback context.
Global functions are verified independently with a fresh frame zero, so an active-frame check cannot identify a global function called from a callback. Also check the complete subprogram call graph during stack-depth validation and reject a function containing a legacy load when any caller is a callback. This covers global and static descendants without making has_ld_abs transitive, preserving its per-function BTF return-type check. Ordinary uses outside callbacks remain supported.
References
- http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-98044
- https://git.kernel.org/stable/c/3484a99303912db62428494a9061212049027e57
- https://git.kernel.org/stable/c/bc489c0c9b8c86bd7fac42cfd1bb152f042fca56
- https://git.kernel.org/stable/c/e7d28823c662128caae63f14e16bd394916c139b
- https://git.kernel.org/stable/c/cebda2a2bb4183550eae9dcf888c16407b4fffda