How severe is CVE-2026-45903?

CVE-2026-45903 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability high.

Is CVE-2026-45903 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (5th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-45903?

CVE-2026-45903 affects Linux Linux Kernel. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-45903?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-45903 have an EU (EUVD) identifier?

Yes. CVE-2026-45903 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-32369.

When was CVE-2026-45903 published?

CVE-2026-45903 was published on 2026-05-27 and last updated on 2026-06-24.

CVE-2026-45903

CVE-2026-45903 is a high-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 7.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-125.

Key facts

Severity: High (CVSS 3.x base score 7.1)
EPSS exploit prediction: 0% (5th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-32369
Weakness: CWE-125
Affected product: Linux Linux Kernel
Published: 2026-05-27
Last modified: 2026-06-24

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix memory access flags in helper prototypes After commit 37cce22dbd51 ("bpf: verifier: Refactor helper access type tracking"), the verifier started relying on the access type flags in helper function prototypes to perform memory access optimizations. Currently, several helper functions utilizing ARG_PTR_TO_MEM lack the corresponding MEM_RDONLY or MEM_WRITE flags. This omission causes the verifier to incorrectly assume that the buffer contents are unchanged across the helper call. Consequently, the verifier may optimize away subsequent reads based on this wrong assumption, leading to correctness issues. For bpf_get_stack_proto_raw_tp, the original MEM_RDONLY was incorrect since the helper writes to the buffer. Change it to ARG_PTR_TO_UNINIT_MEM which correctly indicates write access to potentially uninitialized memory. Similar issues were recently addressed for specific helpers in commit ac44dcc788b9 ("bpf: Fix verifier assumptions of bpf_d_path's output buffer") and commit 2eb7648558a7 ("bpf: Specify access type of bpf_sysctl_get_name args"). Fix these prototypes by adding the correct memory access flags.

Frequently asked questions

What is CVE-2026-45903?: In the Linux kernel, the following vulnerability has been resolved: bpf: Fix memory access flags in helper prototypes After commit 37cce22dbd51 ("bpf: verifier: Refactor helper access type tracking"), the verifier started relying on the access type flags in helper function prototypes to perform memory access optimizations. Currently, several helper functions utilizing ARG_PTR_TO_MEM lack the corresponding MEM_RDONLY or MEM_WRITE flags. This omission causes the verifier to incorrectly assume that the buffer contents are unchanged across the helper call. Consequently, the verifier may optimize away subsequent reads based on this wrong assumption, leading to correctness issues. For bpf_get_stack_proto_raw_tp, the original MEM_RDONLY was incorrect since the helper writes to the buffer. Change it to ARG_PTR_TO_UNINIT_MEM which correctly indicates write access to potentially uninitialized memory. Similar issues were recently addressed for specific helpers in commit ac44dcc788b9 ("bpf: Fix verifier assumptions of bpf_d_path's output buffer") and commit 2eb7648558a7 ("bpf: Specify access type of bpf_sysctl_get_name args"). Fix these prototypes by adding the correct memory access flags.
How severe is CVE-2026-45903?: CVE-2026-45903 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability high.
Is CVE-2026-45903 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (5th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-45903?: CVE-2026-45903 affects Linux Linux Kernel. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-45903?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-45903 have an EU (EUVD) identifier?: Yes. CVE-2026-45903 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-32369.
When was CVE-2026-45903 published?: CVE-2026-45903 was published on 2026-05-27 and last updated on 2026-06-24.

References

Affected products (1)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

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