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NVD / CVE Program· CNA Linux

CVE-2026-89476: sctp: fix stream->outcnt underflow on duplicate RECONF responses

Noroxi assessment

Priority: Monitor (action score 30/100)

  • 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: 0.69% (FIRST EPSS); higher than 53% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: Linux Linux 041f7df5a929d3e7435dd8387e8ea17f2d412b7d, 092acd3c55a4077b00489064615d8d2d898daf91, 2d867663c563e8009257b9edf9c8ec75d9bbf19a; 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 041f7df5a929d3e7435dd8387e8ea17f2d412b7d, 092acd3c55a4077b00489064615d8d2d898daf91, 2d867663c563e8009257b9edf9c8ec75d9bbf19a; 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: sctp: fix stream->outcnt underflow on duplicate RECONF responses A cached RECONF chunk may contain more than one request parameter. A duplicate response can therefore find and process the same ADD_OUT request again while another parameter is still outstanding, rolling back outcnt twice and possibly underflowing it. Track outstanding request types as bits and clear each bit after its first response. Later responses for the same request are then ignored.

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Sep 11, 2026
Updated
Oct 19, 2026
EPSS
0.6% · 53th percentile
CWE
—

Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.6%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.5
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-2026-89476

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

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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

    • 4.12affected
    • 11ae76e67a179f25ae8f772d62a7ddf717b1cdf3 and later · before 041f7df5a929d3e7435dd8387e8ea17f2d412b7daffected · git
    • 11ae76e67a179f25ae8f772d62a7ddf717b1cdf3 and later · before 59f61c39cb99ee1737bd742a20094fe5653389bbaffected · git
    • 11ae76e67a179f25ae8f772d62a7ddf717b1cdf3 and later · before 793519e343867ee9a3e84f6cac07f81f2aec7b5daffected · git
    • 11ae76e67a179f25ae8f772d62a7ddf717b1cdf3 and later · before 092acd3c55a4077b00489064615d8d2d898daf91affected · git
    • 11ae76e67a179f25ae8f772d62a7ddf717b1cdf3 and later · before 2d867663c563e8009257b9edf9c8ec75d9bbf19aaffected · git
    • 11ae76e67a179f25ae8f772d62a7ddf717b1cdf3 and later · before d02a5794c3deedcb8476d017fcee2b7aaedab2e1affected · git
    • 11ae76e67a179f25ae8f772d62a7ddf717b1cdf3 and later · before 8320cbd81bc21a1ca6ebdf70ad610ebc5ef1bd68affected · git
    • 11ae76e67a179f25ae8f772d62a7ddf717b1cdf3 and later · before 3faf13aff243ca9f78d08b1a2956ef5a6fc77b6eaffected · git
    • before 4.12not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.190-16.1.190-1
Debian:12linux-6.12before 6.12.111-1~deb12u16.12.111-1~deb12u1
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.2.6-17.2.6-1

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-2026-89474Sep 11, 2026 · power: supply: bq256xx: drain usb_work before freeing the charger
    0Monitor
  • ← EarlierCVE-2026-89475Sep 11, 2026 · power: supply: bq24257: fix use-after-free on remove
    0Monitor
  • Later →CVE-2026-89477Sep 11, 2026 · sctp: fix NULL deref on untransmitted RECONF completion
    30Monitor

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 Linux041f7df5a929d3e7435dd8387e8ea17f2d412b7dVendor (CNA)
Linux Linux092acd3c55a4077b00489064615d8d2d898daf91Vendor (CNA)
Linux Linux2d867663c563e8009257b9edf9c8ec75d9bbf19aVendor (CNA)
Linux Linux3faf13aff243ca9f78d08b1a2956ef5a6fc77b6eVendor (CNA)
Linux Linux59f61c39cb99ee1737bd742a20094fe5653389bbVendor (CNA)
Linux Linux793519e343867ee9a3e84f6cac07f81f2aec7b5dVendor (CNA)
Linux Linux8320cbd81bc21a1ca6ebdf70ad610ebc5ef1bd68Vendor (CNA)
Linux Linuxd02a5794c3deedcb8476d017fcee2b7aaedab2e1Vendor (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:linux6.1.190-1 · Debian:12Package registry (OSV)
debian:linux6.12.111-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.111-1~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+1% in 7 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

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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. SSVC exploitation— → none
  2. 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