CVE-2025-38463 Vulnerability Analysis & Exploit Details

CVE-2025-38463
Vulnerability Scoring

Analysis In Progress
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-2025-38463 Details

Status: Received on 25 Jul 2025, 16:15 UTC

Published on: 25 Jul 2025, 16:15 UTC

CVSS Release:

CVE-2025-38463 Vulnerability Summary

CVE-2025-38463: In the Linux kernel, the following vulnerability has been resolved: tcp: Correct signedness in skb remaining space calculation Syzkaller reported a bug [1] where sk->sk_forward_alloc can overflow. When we send data, if an skb exists at the tail of the write queue, the kernel will attempt to append the new data to that skb. However, the code that checks for available space in the skb is flawed: ''' copy = size_goal - skb->len ''' The types of the variables involved are: ''' copy: ssize_t (s64 on 64-bit systems) size_goal: int skb->len: unsigned int ''' Due to C's type promotion rules, the signed size_goal is converted to an unsigned int to match skb->len before the subtraction. The result is an unsigned int. When this unsigned int result is then assigned to the s64 copy variable, it is zero-extended, preserving its non-negative value. Consequently, copy is always >= 0. Assume we are sending 2GB of data and size_goal has been adjusted to a value smaller than skb->len. The subtraction will result in copy holding a very large positive integer. In the subsequent logic, this large value is used to update sk->sk_forward_alloc, which can easily cause it to overflow. The syzkaller reproducer uses TCP_REPAIR to reliably create this condition. However, this can also occur in real-world scenarios. The tcp_bound_to_half_wnd() function can also reduce size_goal to a small value. This would cause the subsequent tcp_wmem_schedule() to set sk->sk_forward_alloc to a value close to INT_MAX. Further memory allocation requests would then cause sk_forward_alloc to wrap around and become negative. [1]: https://syzkaller.appspot.com/bug?extid=de6565462ab540f50e47

Assessing the Risk of CVE-2025-38463

Access Complexity Graph

The exploitability of CVE-2025-38463 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-2025-38463

No exploitability data is available for CVE-2025-38463.

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-2025-38463, 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-2025-38463, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: None
    CVE-2025-38463 does not compromise confidentiality.
  • Integrity: None
    CVE-2025-38463 does not impact data integrity.
  • Availability: None
    CVE-2025-38463 does not affect system availability.

CVE-2025-38463 References

External References

CWE Common Weakness Enumeration

Unknown

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