CVE-2026-98084
In the Linux kernel, the following vulnerability has been resolved: bpf: backtracking shouldn't clear outer frame R1-R5 for callbacks When processing calls to bpf_loop() verifier marks R1 (and R4…
Overview
CVE-2026-98084 is a known-severity vulnerability. It was published on September 25, 2026.
Technical description
In the Linux kernel, the following vulnerability has been resolved:
bpf: backtracking shouldn't clear outer frame R1-R5 for callbacks
When processing calls to bpf_loop() verifier marks R1 (and R4) as
precise. R1 tracks loop iterations number and because of the
'callback_depth < R1' mechanics in check_helper_call() must be marked
precise. However, precision propagation for R1 was broken,
when bpf_loop() call was verified on a second iteration.
Consider the following verification trace:
- main: bpf_loop(nr_loops, callback ...)
- callback: BPF_EXIT
- main: bpf_loop(nr_loops, callback ...)
- ...
While the first visit of the call to bpf_loop() propagated R1
precision as expected, the second call to mark_chain_precision() in
the check_helper_call() set R1, but it was immediately reset when
backtrack_insn() processed preceding BPF_EXIT in the loop deleted in
this patch.
Because of that, the second visit of the call to bpf_loop() injected
checkpoint with R1 not marked as precise. Which co
Remediation
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
References
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Frequently asked questions
What is CVE-2026-98084?
CVE-2026-98084 is a known-severity vulnerability. It was published on September 25, 2026.
How severe is CVE-2026-98084?
CVSS score information is not yet available for this vulnerability. Check back as the CVE record is updated by NVD analysts.
How do I fix or remediate CVE-2026-98084?
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-98084?
CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-98084 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.