CVE-2025-71085 Linux CVE debrief

Who should care

Users of Linux kernel versions 4.8.1 to 6.18.4, and 6.19 rc1 to rc8, should apply patches or consider compensating controls. Operators, platform administrators, vulnerability management teams, and security teams should review the vulnerability and assess their exposure. They should also verify whether affected product deployments exist in their managed environments.

Technical summary

The Linux kernel vulnerability CVE-2025-71085 was caused by an implicit integer cast in __skb_cow(). The check (headroom > skb_headroom(skb)) was meant to ensure that delta = headroom - skb_headroom(skb) is never negative. However, if headroom > INT_MAX and delta <= -NET_SKB_PAD, the check passes, delta becomes negative, and pskb_expand_head() is passed a negative value for nhead. Fix the trigger condition in calipso_skbuff_setattr(). Avoid passing 'negative' headroom sizes to skb_cow() within calipso_skbuff_setattr() by only using skb_cow() to grow headroom.

Defensive priority

Medium priority, as the vulnerability has been patched and CVSS score is 5.5

Recommended defensive actions

• Apply patches from Linux kernel stable branches
• Inventory and update vulnerable Linux kernel versions
• Monitor for potential exploitation attempts
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record was published on 2026-01-13T16:16:08.117Z and last modified on 2026-07-14T13:18:02.087Z. The NVD entry is currently Modified. Evidence limits suggest that Linux kernel versions 4.8.1 to 6.18.4, and 6.19 rc1 to rc8, may be affected. However, verification is needed to confirm affected deployments and assess actual exposure.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.