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CVE.org (no NVD analysis yet)· CNA Linux

CVE-2026-99213: vsock: treat TCP_CLOSING as once-established

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 44d1ca05d6094a5d75c671a0545249186d790b8d, 4f6ac74fa594a918d41255c941256e1d51592d3b, 5f2ab77028602a22f0cc33cac063a313787cbeae; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.159.1-1 on Azure Linux 3.0 6.6.161.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 44d1ca05d6094a5d75c671a0545249186d790b8d, 4f6ac74fa594a918d41255c941256e1d51592d3b, 5f2ab77028602a22f0cc33cac063a313787cbeae; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.159.1-1 on Azure Linux 3.0 6.6.161.1-1 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: vsock: treat TCP_CLOSING as once-established Handle the TCP_ESTABLISHED -> TCP_CLOSING transition on OP_RST, which can race with the connect loop. Immediately break and return 0 on ESTABLISHED/CLOSING. The return value of connect() should reflect what happened up to the point the connection was established or failed. Events that occur afterwards must not affect it. E.g. even if OP_RW has already set sk_err, connect() should still return 0, not ENOBUFS because of it. Adapt the inaccurate comment above signal_pending(). Resetting a socket that is still present in connected_table can lead to memory corruption. The reporter noted lost transports for in-flight skbs, and I have reproduced crashes caused by re-insertion into connected_table. list_add double add: new=, prev=, next=. kernel BUG at lib/list_debug.c:35! Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI Workqueue: vsock-loopback vsock_loopback_work RIP: 0010:__list_add_valid_or_report+0x11f/0x130 Call Trace: vsock_insert_connected.cold+0xe/0x13 virtio_transport_recv_pkt+0x10e9/0x1460 vsock_loopback_work+0x305/0x480 process_one_work+0xe4c/0x1560 worker_thread+0x4f1/0xd60 kthread+0x36e/0x470 ret_from_fork+0x47b/0x6b0 ret_from_fork_asm+0x1a/0x30 This fix is supplementary to commit 002541ef650b ("vsock: Ignore signal/timeout on connect() if already established"). Details under Link.

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Oct 28, 2026
Updated
Oct 31, 2026
EPSS
0.1% · 2th percentile
CWE
—

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%

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.

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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.

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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

    • 3.9affected
    • d021c344051af91f42c5ba9fdedc176740cbd238 and later · before ea36ef3c229d54b552432d1290aee1d807f67fd5affected · git
    • d021c344051af91f42c5ba9fdedc176740cbd238 and later · before 5f2ab77028602a22f0cc33cac063a313787cbeaeaffected · git
    • d021c344051af91f42c5ba9fdedc176740cbd238 and later · before f89770c7365748d9d6a2ae07d1c23497ca21ec07affected · git
    • d021c344051af91f42c5ba9fdedc176740cbd238 and later · before deb972c7eea8d0bc3109c35c30a1c86d4939f811affected · git
    • d021c344051af91f42c5ba9fdedc176740cbd238 and later · before baf1b5715640e434249ce7f63f94bd1a00938ef9affected · git
    • d021c344051af91f42c5ba9fdedc176740cbd238 and later · before c2c5359ef2c33684fa3f3652fd761a483db8d1e7affected · git
    • d021c344051af91f42c5ba9fdedc176740cbd238 and later · before 44d1ca05d6094a5d75c671a0545249186d790b8daffected · git
    • d021c344051af91f42c5ba9fdedc176740cbd238 and later · before 4f6ac74fa594a918d41255c941256e1d51592d3baffected · git
    • before 3.9not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:13linuxbefore 6.12.115-26.12.115-2
Debian:14linuxbefore 7.2.13-17.2.13-1

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-2026-99211Oct 28, 2026 · netlink: reset skb headers before unicast and multicast filtering
    0Monitor
  • ← EarlierCVE-2026-99212Oct 28, 2026 · net/rds: don't let the rdma_cm destroy an id RDS still owns on route failure
    28Monitor
  • Later →CVE-2026-99214Oct 28, 2026 · drm/vc4: hdmi: Move packet RAM enable to PM runtime
    0Monitor

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 Linux44d1ca05d6094a5d75c671a0545249186d790b8dVendor (CNA)
Linux Linux4f6ac74fa594a918d41255c941256e1d51592d3bVendor (CNA)
Linux Linux5f2ab77028602a22f0cc33cac063a313787cbeaeVendor (CNA)
Linux Linuxbaf1b5715640e434249ce7f63f94bd1a00938ef9Vendor (CNA)
Linux Linuxc2c5359ef2c33684fa3f3652fd761a483db8d1e7Vendor (CNA)
Linux Linuxdeb972c7eea8d0bc3109c35c30a1c86d4939f811Vendor (CNA)
Linux Linuxea36ef3c229d54b552432d1290aee1d807f67fd5Vendor (CNA)
Linux Linuxf89770c7365748d9d6a2ae07d1c23497ca21ec07Vendor (CNA)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
azl3 kernel 6.6.159.1-1 on Azure Linux 3.06.6.161.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.12.115-2 · Debian:13Package 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.

  1. Published
  2. Fix recordedsame day
  3. TodayNov 11, 2026+14 d
EPSS, last 120 days

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

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

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

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

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

All national notices →

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)

—

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.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. CVSS— → 7.8
  2. Severity— → high
  3. Exploit maturity— → none
  4. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (7 more)

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

All records