Linux Kernel up to 7.2.6/7.3-rc1 BPF backtrack_insn memory corruption

Summaryinfo

A vulnerability, which was classified as very critical, was found in Linux Kernel up to 7.2.6/7.3-rc1. This affects the function backtrack_insn of the component BPF. The manipulation results in memory corruption. This vulnerability is identified as CVE-2026-98085. The attack can be executed remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as very critical, was found in Linux Kernel up to 7.2.6/7.3-rc1. Affected is the function backtrack_insn of the component BPF. The manipulation with an unknown input leads to a memory corruption vulnerability. CWE is classifying the issue as CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: bpf: backtrack_insn(): Handle ld_{abs,ind} subprog exit edge Nicholas Carlini reported a bug in precision backtracking mechanism for BPF_LD | BPF_{IND,ABS} instructions. These instructions are modelled as two branches: - fallthrough; - implicit exit from current subprogram. The implicit exit case was not handled by the backtrack_insn() function. When backtracking such a path backtrack_insn() did not call bt_subprog_enter(), which meant that backtracking continued manipulating precision marks in a caller frame, while looking at instructions in a callee frame. This lead to segmentation faults during verification (see the selftest), or unsound state pruning.

The advisory is available at git.kernel.org. This vulnerability is traded as CVE-2026-98085 since 09/25/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation needs additional levels of successful authentication. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $5k-$25k at the moment (estimation calculated on 09/25/2026).

Upgrading to version 7.2.7 or 7.3-rc2 eliminates this vulnerability. Applying the patch 671b7b9a660ef15b25faa3df161205b9dc8d1eb2/387b1baefbb776e3f48dc2261e77a49213f470f7 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3
• 7.2.4
• 7.2.5
• 7.2.6
• 7.3-rc1

License

• open-source

Website

• Vendor: https://www.kernel.org/

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