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Networks

CVE-2026-72251

9.8
Critical
EPSS 0.71%Patch availableAug 17, 2026

Linux netfilter SIP NAT bug can cause memory corruption leading to remote code execution.

common questions

Is CVE-2026-72251 being exploited?

Not confirmed. CVE-2026-72251 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.71% probability of exploitation in the next 30 days.

How severe is CVE-2026-72251?

CVE-2026-72251 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2026-72251?

Yes. A fix has been recorded for CVE-2026-72251. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.

What does CVE-2026-72251 affect?

CVE-2026-72251 affects Linux kernel (netfilter nf_nat_sip), VoIP gateways, Routers/firewalls using SIP NAT helper, Systems performing SIP NAT via conntrack. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

What should I do about CVE-2026-72251?

Apply kernel security update or disable nf_nat_sip; block SIP NAT traffic until patched.

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

executive summary
technical analysis
affected
Linux kernel (netfilter nf_nat_sip)VoIP gatewaysRouters/firewalls using SIP NAT helperSystems performing SIP NAT via conntrack
impact

Remote attackers sending crafted SIP packets can trigger skb pointer reuse, causing kernel memory corruption, potential RCE or system crash.

action required

Immediate action required

affected versions
Linux Linux
  • affected>= 7266507d89991fa1e989283e4e032c6d9357fe26 and < bded21a4bf9bf86a79148be735723a97ca9a7532
  • affected>= 7266507d89991fa1e989283e4e032c6d9357fe26 and < dc11f26685aa850f237226f0f463647aea58ab7c
  • affected>= 7266507d89991fa1e989283e4e032c6d9357fe26 and < e38143c9b477f2968024c47c647dd4456a40aff1
  • affected>= 7266507d89991fa1e989283e4e032c6d9357fe26 and < 57e4e29644ec054d7021d296407e7ddd844afea2
  • affected>= 7266507d89991fa1e989283e4e032c6d9357fe26 and < eae9c6ccb5af69c713a65f8ae219f5c1aa32cd17
  • affected>= 7266507d89991fa1e989283e4e032c6d9357fe26 and < 2bcf2c5052fb5e73e255140ab43f056aef409c27
  • affected>= 7266507d89991fa1e989283e4e032c6d9357fe26 and < 0e76e3e886cc9ee027337d5ad39cb96f57b7bdc7
  • affected>= 7266507d89991fa1e989283e4e032c6d9357fe26 and < 77e43bcb7ec177e293a5c3f1b91a2c5aebfb6c68
  • affected3.9
vendor says fixed in< 3.9, >= 5.10.261 and <= 5.10.*, >= 5.15.212 and <= 5.15.*, >= 6.1.178 and <= 6.1.*, >= 6.6.145 and <= 6.6.*, >= 6.12.97 and <= 6.12.*, >= 6.18.40 and <= 6.18.*, >= 7.1.5 and <= 7.1.*, >= 7.2 and <= *

As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.

how to fix
Remediation steps are tailored for users whose stack is affected. Add this technology to your stack to see the fix checklist.
references
NVDCVE.orgCVE DetailsSource
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