CVE-2026-63836
Vulnerability Scoring
Analysis In Progress
CVE-2026-63836 Vulnerability Analysis & Exploit Details
CVE-2026-63836
Attack Complexity Details
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Attack Complexity:
Attack Complexity Analysis In Progress
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Attack Vector:
Attack Vector Under Analysis
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Privileges Required:
None
No authentication is required for exploitation.
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Scope:
Impact is confined to the initially vulnerable component.
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User Interaction:
None
No user interaction is necessary for exploitation.
CVE-2026-63836 Details
Status: Received on 19 Jul 2026, 12:16 UTC
Published on: 19 Jul 2026, 12:16 UTC
CVSS Release:
CVE-2026-63836 Vulnerability Summary
CVE-2026-63836: In the Linux kernel, the following vulnerability has been resolved: batman-adv: tp_meter: avoid divide-by-zero for dec_cwnd The cwnd is always MSS <= cwnd <= 0x20000000. But the calculation in batadv_tp_update_cwnd() assumes unsigned 32 bit arithmetics. ((mss * 8) ** 2) / (cwnd * 8) In case cwnd is actually 0x20000000, it will be shifted by 3 bit to the left end up at 0x100000000 or U32_MAX + 1. It will therefore wrap around and be 0 - resulting in: ((mss * 8) ** 2) / 0 This is of course invalid and cannot be calculated. The calculation should must be simplified to avoid this overflow: (mss ** 2) * 8 / cwnd It will keep the precision enhancement from the scaling (by 8) but avoid the overflow in the divisor. In theory, there could still be an overflow in the dividend. It is at the moment fixed to BATADV_TP_PLEN in batadv_tp_recv_ack() - so it is not an imminent problem. But allowing it to use the whole u32 bit range, would mean that it can still use up to 67 bits. To keep this calculation safe for 32 bit arithmetic, mss must never use more than floor((32 - 3) / 2) bits - or in other words: must never be larger than 16383.
Assessing the Risk of CVE-2026-63836
Access Complexity Graph
The exploitability of CVE-2026-63836 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-2026-63836
No exploitability data is available for CVE-2026-63836.
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-2026-63836, 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-2026-63836, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.
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Confidentiality:
None
CVE-2026-63836 does not compromise confidentiality.
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Integrity:
None
CVE-2026-63836 does not impact data integrity.
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Availability:
None
CVE-2026-63836 does not affect system availability.
CVE-2026-63836 References
External References
- https://git.kernel.org/stable/c/1381b021bf886b793fa5ffb895a8efae7ba0318f
- https://git.kernel.org/stable/c/33ccd52f3cc9ed46ce395199f89aa3234dc83314
- https://git.kernel.org/stable/c/35264c4d46067d6312871488c810cef387f8c1f6
- https://git.kernel.org/stable/c/585616dab0aa9c45bc11b2c8082ca78533bc00e9
- https://git.kernel.org/stable/c/7d2a44bc6bbe39aed03c68864aa0e54e04a50278
- https://git.kernel.org/stable/c/ac229c86e49fdb96d91f51bc2fa37a9c4f58c44f
- https://git.kernel.org/stable/c/cd74176cf1685f35a2e5f212d15748bbfecb53b6
- https://git.kernel.org/stable/c/d08b69da40a101df1e28bfe1e8fa7a09ffa41107
CWE Common Weakness Enumeration
Unknown
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