Linux Kernel up to 7.2.6/7.3-rc1 BPF check_map_kptr_access state issue

Summaryinfo

A vulnerability was found in Linux Kernel up to 7.2.6/7.3-rc1. It has been rated as very critical. The affected element is the function check_map_kptr_access of the component BPF. This manipulation causes state issue. This vulnerability appears as CVE-2026-98034. The attack may be initiated remotely. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 7.2.6/7.3-rc1 and classified as very critical. Affected by this vulnerability is the function check_map_kptr_access of the component BPF. The manipulation with an unknown input leads to a state issue vulnerability. The CWE definition for the vulnerability is CWE-371. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: bpf: Mark NULL kptr stores precise check_map_kptr_access() permits a scalar store into an untrusted kptr field only when the register is known to contain zero. Unlike other verifier checks whose outcome depends on a scalar value, it does not mark that register precise. A state checkpoint reached with an imprecise zero can therefore prune a second path that reaches the store with an arbitrary nonzero scalar. The program can write attacker-controlled bits into the kptr field and load them back as a PTR_TO_BTF_ID. Call mark_chain_precision() before accepting a known-zero register. This forces state equivalence to compare its scalar range and makes the verifier visit and reject a path carrying a nonzero value.

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2026-98034 since 09/25/2026. The exploitation appears to be easy. The attack can be launched remotely. Additional levels of successful authentication are necessary for exploitation. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k 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 86168208737bdd267d92d855d453d1d2f840df19/ecdc5043794c9184aa8e6c814603899479c46b35 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Discussion