CVE-2025-38591 Vulnerability Analysis & Exploit Details

CVE-2025-38591
Vulnerability Scoring

Analysis In Progress

Attack Complexity Details

Attack Complexity:
Attack Complexity Analysis In Progress
Attack Vector:
Attack Vector Under Analysis
Privileges Required: None
No authentication is required for exploitation.
Scope:
Impact is confined to the initially vulnerable component.
User Interaction: None
No user interaction is necessary for exploitation.

CVE-2025-38591 Details

Status: Awaiting Analysis

Last updated: 🕝 20 Aug 2025, 14:40 UTC
Originally published on: 🕔 19 Aug 2025, 17:15 UTC

CVSS Release:

CVE-2025-38591 Vulnerability Summary

CVE-2025-38591: In the Linux kernel, the following vulnerability has been resolved: bpf: Reject narrower access to pointer ctx fields The following BPF program, simplified from a syzkaller repro, causes a kernel warning: r0 = *(u8 *)(r1 + 169); exit; With pointer field sk being at offset 168 in __sk_buff. This access is detected as a narrower read in bpf_skb_is_valid_access because it doesn't match offsetof(struct __sk_buff, sk). It is therefore allowed and later proceeds to bpf_convert_ctx_access. Note that for the "is_narrower_load" case in the convert_ctx_accesses(), the insn->off is aligned, so the cnt may not be 0 because it matches the offsetof(struct __sk_buff, sk) in the bpf_convert_ctx_access. However, the target_size stays 0 and the verifier errors with a kernel warning: verifier bug: error during ctx access conversion(1) This patch fixes that to return a proper "invalid bpf_context access off=X size=Y" error on the load instruction. The same issue affects multiple other fields in context structures that allow narrow access. Some other non-affected fields (for sk_msg, sk_lookup, and sockopt) were also changed to use bpf_ctx_range_ptr for consistency. Note this syzkaller crash was reported in the "Closes" link below, which used to be about a different bug, fixed in commit fce7bd8e385a ("bpf/verifier: Handle BPF_LOAD_ACQ instructions in insn_def_regno()"). Because syzbot somehow confused the two bugs, the new crash and repro didn't get reported to the mailing list.

Assessing the Risk of CVE-2025-38591

Access Complexity Graph

The exploitability of CVE-2025-38591 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).

Exploitability Analysis for CVE-2025-38591

No exploitability data is available for CVE-2025-38591.

Understanding AC and PR

A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.

Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.

Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.

CVSS Score Breakdown Chart

Above is the CVSS Sub-score Breakdown for CVE-2025-38591, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.

CIA Impact Analysis

Below is the Impact Analysis for CVE-2025-38591, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

Confidentiality: None
CVE-2025-38591 does not compromise confidentiality.
Integrity: None
CVE-2025-38591 does not impact data integrity.
Availability: None
CVE-2025-38591 does not affect system availability.

CVE-2025-38591 References

External References

CWE Common Weakness Enumeration

Unknown

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