Skip to content
Noroxi
NVD / CVE Program· CNA Linux

CVE-2026-64581: xfrm: fix sk_dst_cache double-free in xfrm_user_policy()

HighCVSS 7.8 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 31/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.12% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 0ea8f06454012d9e7f9c6e6253df710949bf6294, 3.17, 3.19; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 6.6.157.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 0ea8f06454012d9e7f9c6e6253df710949bf6294, 3.17, 3.19; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 6.6.157.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: xfrm: fix sk_dst_cache double-free in xfrm_user_policy() xfrm_user_policy() clears the socket dst cache with __sk_dst_reset(), i.e. the non-atomic __sk_dst_set(sk, NULL): it reads sk_dst_cache with rcu_dereference_protected(), stores NULL and dst_release()s the old dst. That is only safe if no other thread modifies sk_dst_cache concurrently. For a connected UDP socket that does not hold: the transmit fast path (udp_sendmsg -> sk_dst_check -> sk_dst_reset) resets the cache locklessly with an atomic xchg(). A per-socket policy change racing a send can make both sides observe the same old dst and each dst_release() it, dropping the socket's single reference twice and freeing the xfrm_dst bundle while it is still referenced: BUG: KASAN: slab-use-after-free in dst_release Write of size 4 at addr ffff88801897b6c0 by task exploit/155 Call Trace: ... dst_release (... ./include/linux/rcuref.h:109) xfrm_user_policy (./include/net/sock.h:2239 ./include/net/sock.h:2256 net/xfrm/xfrm_state.c:3053) do_ip_setsockopt (net/ipv4/ip_sockglue.c:1347) ip_setsockopt (net/ipv4/ip_sockglue.c:1417) do_sock_setsockopt (net/socket.c:2368) __sys_setsockopt (net/socket.c:2393) __x64_sys_setsockopt (net/socket.c:2396) do_syscall_64 (arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) Reachable by an unprivileged user via a user+network namespace. Use the atomic sk_dst_reset() so the cache is cleared and released with a single xchg(): whichever side wins releases the dst once, the other sees NULL and does nothing. Behaviour is otherwise unchanged.

Published
Aug 5, 2026
Updated
Oct 19, 2026
EPSS
0.1% · 1th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-64581

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits every 10 minutes on paid plans, on the hour on the free plan.

Your free account also gets you

  • CVE alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools, at most 30 a day (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every MondayDon't want an account? RSS feed for linux records
Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

We use this product, ask for help

Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 72f157be2f81910ae759bfe2e5c2256fc4625645, 9e9fe58a92a46c6d154d2901735bf230d91b8507, adc1ec6cdc20d430aa01b86497220709b9149466, b54033eb1cfd77aba471269ddd804ed8d3e35dea, c9e82cb34c3c2ee895af01bc899c6ed0bc6eb04a, 5eef9b51114fcc65651d671add52f267f91b9451, 4.14affected
    • 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 and later · before e8686fd8d18b99f3a9038683045b2f2338a7706daffected · git
    • 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 and later · before a9340ebdc13f8bb5063c0bc0b037ee7e640d4ae9affected · git
    • 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 and later · before f833821e4b52ab6335d443ede5fb79c38e61d19aaffected · git
    • 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 and later · before f0ab9a71167bae308e05ab13b65e2007504a603faffected · git
    • 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 and later · before 8dd8929b71c4f06c614f8f54c2cc070453faae16affected · git
    • 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 and later · before 0ea8f06454012d9e7f9c6e6253df710949bf6294affected · git
    • 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 and later · before 96b678d08268b5f5c6fc99d4289d9b7e334fc683affected · git
    • 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 and later · before c283e9ada7fcb7dd4b10592623086b2e6d2f9925affected · git
    • 3.16.52 and later · before 3.17affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.187-16.1.187-1
Debian:12linux-6.12before 6.12.107-1~deb12u16.12.107-1~deb12u1
Debian:13linuxbefore 6.12.107-16.12.107-1
Debian:14linuxbefore 7.1.6-17.1.6-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-64579Aug 5, 2026 · xfrm: policy: preallocate inexact bins before xfrm_hash_rebuild reinsert
    0Monitor
  • ← EarlierCVE-2026-64580Aug 5, 2026 · xfrm6: clear dst.dev on error to avoid double netdev_put in xfrm6_fill_dst()
    31Monitor
  • Later →CVE-2026-64582Aug 5, 2026 · RDMA/rxe: Fix a use-after-free problem in rxe_mmap
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux0ea8f06454012d9e7f9c6e6253df710949bf6294Vendor (CNA)
Linux Linux3.17Vendor (CNA)
Linux Linux3.19Vendor (CNA)
Linux Linux4.10Vendor (CNA)
Linux Linux4.2Vendor (CNA)
Linux Linux4.5Vendor (CNA)
Linux Linux8dd8929b71c4f06c614f8f54c2cc070453faae16Vendor (CNA)
Linux Linux96b678d08268b5f5c6fc99d4289d9b7e334fc683Vendor (CNA)
Linux Linuxa9340ebdc13f8bb5063c0bc0b037ee7e640d4ae9Vendor (CNA)
Linux Linuxc283e9ada7fcb7dd4b10592623086b2e6d2f9925Vendor (CNA)
Linux Linuxe8686fd8d18b99f3a9038683045b2f2338a7706dVendor (CNA)
Linux Linuxf0ab9a71167bae308e05ab13b65e2007504a603fVendor (CNA)
Linux Linuxf833821e4b52ab6335d443ede5fb79c38e61d19aVendor (CNA)
azl3 kernel 6.6.150.1-1 on Azure Linux 3.0—Microsoft (MSRC)
azl3 kernel 6.6.152.1-1 on Azure Linux 3.06.6.157.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.1.187-1 · Debian:12Package registry (OSV)
debian:linux-6.126.12.107-1~deb12u1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-7206410 days apartnet: mana: Sync page pool RX frags for CPU
    39Monitor
  • CVE-2026-645611 days apartKVM: x86: Check for invalid/obsolete root *after* making MMU pages available
    35Monitor
  • CVE-2026-683295 days apartiommu/amd: Wait for completion instead of returning early in iommu_completion_wait()
    35Monitor
  • CVE-2026-681385 days apartnet/sched: serialize qdisc_rtab_list against concurrent get/put
    31Monitor
  • CVE-2026-682455 days apartdrm/amdgpu: fix lifetime issue of amdgpu_vm_get_task_info_pasid()
    31Monitor
  • CVE-2026-683385 days apartnet/packet: avoid fanout hook re-registration after unregister
    31Monitor

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Not on record for this CVE: patch commit or PR link · researcher credit · public bounty program.

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-362 · Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records