CVE-2025-37821 Vulnerability Analysis & Exploit Details

CVE-2025-37821
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-2025-37821 Details

Status: Awaiting Analysis

Last updated: 🕖 18 May 2025, 07:15 UTC
Originally published on: 🕖 08 May 2025, 07:15 UTC

Time between publication and last update: 9 days

CVSS Release:

CVE-2025-37821 Vulnerability Summary

CVE-2025-37821: In the Linux kernel, the following vulnerability has been resolved: sched/eevdf: Fix se->slice being set to U64_MAX and resulting crash There is a code path in dequeue_entities() that can set the slice of a sched_entity to U64_MAX, which sometimes results in a crash. The offending case is when dequeue_entities() is called to dequeue a delayed group entity, and then the entity's parent's dequeue is delayed. In that case: 1. In the if (entity_is_task(se)) else block at the beginning of dequeue_entities(), slice is set to cfs_rq_min_slice(group_cfs_rq(se)). If the entity was delayed, then it has no queued tasks, so cfs_rq_min_slice() returns U64_MAX. 2. The first for_each_sched_entity() loop dequeues the entity. 3. If the entity was its parent's only child, then the next iteration tries to dequeue the parent. 4. If the parent's dequeue needs to be delayed, then it breaks from the first for_each_sched_entity() loop _without updating slice_. 5. The second for_each_sched_entity() loop sets the parent's ->slice to the saved slice, which is still U64_MAX. This throws off subsequent calculations with potentially catastrophic results. A manifestation we saw in production was: 6. In update_entity_lag(), se->slice is used to calculate limit, which ends up as a huge negative number. 7. limit is used in se->vlag = clamp(vlag, -limit, limit). Because limit is negative, vlag > limit, so se->vlag is set to the same huge negative number. 8. In place_entity(), se->vlag is scaled, which overflows and results in another huge (positive or negative) number. 9. The adjusted lag is subtracted from se->vruntime, which increases or decreases se->vruntime by a huge number. 10. pick_eevdf() calls entity_eligible()/vruntime_eligible(), which incorrectly returns false because the vruntime is so far from the other vruntimes on the queue, causing the (vruntime - cfs_rq->min_vruntime) * load calulation to overflow. 11. Nothing appears to be eligible, so pick_eevdf() returns NULL. 12. pick_next_entity() tries to dereference the return value of pick_eevdf() and crashes. Dumping the cfs_rq states from the core dumps with drgn showed tell-tale huge vruntime ranges and bogus vlag values, and I also traced se->slice being set to U64_MAX on live systems (which was usually "benign" since the rest of the runqueue needed to be in a particular state to crash). Fix it in dequeue_entities() by always setting slice from the first non-empty cfs_rq.

Assessing the Risk of CVE-2025-37821

Access Complexity Graph

The exploitability of CVE-2025-37821 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-2025-37821

No exploitability data is available for CVE-2025-37821.

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-2025-37821, 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-2025-37821, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: None
    CVE-2025-37821 does not compromise confidentiality.
  • Integrity: None
    CVE-2025-37821 does not impact data integrity.
  • Availability: None
    CVE-2025-37821 does not affect system availability.

CVE-2025-37821 References

External References

CWE Common Weakness Enumeration

Unknown

Protect Your Infrastructure against CVE-2025-37821: Combat Critical CVE Threats

Stay updated with real-time CVE vulnerabilities and take action to secure your systems. Enhance your cybersecurity posture with the latest threat intelligence and mitigation techniques. Develop the skills necessary to defend against CVEs and secure critical infrastructures. Join the top cybersecurity professionals safeguarding today's infrastructures.

Other 5 Recently Published CVEs Vulnerabilities

  • CVE-2025-49069 – Cross-Site Request Forgery (CSRF) vulnerability in Cimatti Consulting Contact Forms by Cimatti allows Cross Site Request Forgery.This issue affects...
  • CVE-2025-23105 – An issue was discovered in Samsung Mobile Processor Exynos 2200, 1480, and 2400. A Use-After-Free in the mobile processor leads to privilege escalation.
  • CVE-2025-23099 – An issue was discovered in Samsung Mobile Processor Exynos 1480 and 2400. The lack of a length check leads to out-of-bounds writes.
  • CVE-2025-1051 – Sonos Era 300 Heap-based Buffer Overflow Remote Code Execution Vulnerability. This vulnerability allows network-adjacent attackers to execute arbit...
  • CVE-2025-5086 – A deserialization of untrusted data vulnerability affecting DELMIA Apriso from Release 2020 through Release 2025 could lead to a remote code execution.