NVD / CVE Program· CNA Linux

CVE-2026-31773: Bluetooth: SMP: derive legacy responder STK authentication from MITM state

Noroxi assessment

Priority: Monitor (action score 35/100)

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: 0.27% (FIRST EPSS).
Someone on the same network segment can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
Fixed version: Linux Linux 061ee71ac6b03c9f8432fe49538c3682bfcf4cf3, 0afc846bd80073ffcd2b8040f2b2fafaea3d9f72, 20756fec2f0108cb88e815941f1ffff88dc286fe.

Low priority for now. Upgrade to Linux Linux 061ee71ac6b03c9f8432fe49538c3682bfcf4cf3, 0afc846bd80073ffcd2b8040f2b2fafaea3d9f72, 20756fec2f0108cb88e815941f1ffff88dc286fe 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: Bluetooth: SMP: derive legacy responder STK authentication from MITM state The legacy responder path in smp_random() currently labels the stored STK as authenticated whenever pending_sec_level is BT_SECURITY_HIGH. That reflects what the local service requested, not what the pairing flow actually achieved. For Just Works/Confirm legacy pairing, SMP_FLAG_MITM_AUTH stays clear and the resulting STK should remain unauthenticated even if the local side requested HIGH security. Use the established MITM state when storing the responder STK so the key metadata matches the pairing result. This also keeps the legacy path aligned with the Secure Connections code, which already treats JUST_WORKS/JUST_CFM as unauthenticated.

HighCVSS 8.8 · v3.1—No exploit Fix available

SUSE-SU-2026:2914-1

Published: May 1, 2026
Updated: Oct 19, 2026
EPSS: 0.2% · 20th percentile
CWE: CWE-287

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 35 / 40 · 8.8 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.2%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · Linux: 8.8; 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

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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.

Vendor	Product	CPE
linux	linux kernel	cpe:2.3:o:linux:linux_kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

linux linux kernel3.15.5 and later · before 3.16
linux linux kernel3.16.1 and later · before 5.10.253
linux linux kernel5.11 and later · before 5.15.203
linux linux kernel5.16 and later · before 6.1.168
linux linux kernel6.2 and later · before 6.6.134
linux linux kernel6.7 and later · before 6.12.81
linux linux kernel6.13 and later · before 6.18.22
linux linux kernel6.19 and later · before 6.19.12
linux linux kernel3.16
linux linux kernel7.0

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
- 14ec593d6bb050cf40a4ade2f9ac9ca050e0412c, 3.16affected
- fff3490f47810e2d34b91fb9e31103e923b11c2f and later · before 9a38659a3d06080715691bd3139f9c4b61f688e3affected · git
- fff3490f47810e2d34b91fb9e31103e923b11c2f and later · before 667f44f1392df6482483756458c48670e579e9ffaffected · git
- fff3490f47810e2d34b91fb9e31103e923b11c2f and later · before 929db734d12db41ca5f95424db4612397f1bd4a7affected · git
- fff3490f47810e2d34b91fb9e31103e923b11c2f and later · before b1c6a8e554a39b222c0879a288ea98e338fc4d77affected · git
- fff3490f47810e2d34b91fb9e31103e923b11c2f and later · before 0afc846bd80073ffcd2b8040f2b2fafaea3d9f72affected · git
- fff3490f47810e2d34b91fb9e31103e923b11c2f and later · before 061ee71ac6b03c9f8432fe49538c3682bfcf4cf3affected · git
- fff3490f47810e2d34b91fb9e31103e923b11c2f and later · before 9a6d0db176f082685e0b6149700c0baf3ce2aa8baffected · git
- fff3490f47810e2d34b91fb9e31103e923b11c2f and later · before 20756fec2f0108cb88e815941f1ffff88dc286feaffected · git
- 3.15.5 and later · before 3.16affected · semver

Package-level exposure

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

Ecosystem	Package	Affected range	Fix
Debian:12	linux	before 6.1.170-1	6.1.170-1
Debian:13	linux	before 6.12.85-1	6.12.85-1
Debian:14	linux	before 6.19.12-1	6.19.12-1
SUSE:Linux Enterprise Live Patching 12 SP5	kernel-default	before 4.12.14-122.320.1	4.12.14-122.320.1
SUSE:Linux Enterprise Live Patching 12 SP5	kgraft-patch-SLE12-SP5_Update_85	before 1-8.3.1	1-8.3.1
SUSE:Linux Enterprise Server 12 SP5-LTSS	kernel-source	before 4.12.14-122.320.1	4.12.14-122.320.1
SUSE:Linux Enterprise Server 12 SP5-LTSS	kernel-syms	before 4.12.14-122.320.1	4.12.14-122.320.1

Same product

linux: all records

Other highest-scoring records for the same primary product.

CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
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CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
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CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
85Now

Published before and after this one in the same product

← EarlierCVE-2026-31771May 1, 2026 · Bluetooth: hci_event: move wake reason storage into validated event handlers
32Monitor
← EarlierCVE-2026-31772May 1, 2026 · Bluetooth: hci_sync: fix stack buffer overflow in hci_le_big_create_sync
31Monitor
Later →CVE-2026-31774May 1, 2026 · io_uring/net: fix slab-out-of-bounds read in io_bundle_nbufs()
28Monitor

Remediation

Which version to upgrade to

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

Product / package	Fixed version	Source
Linux Linux	061ee71ac6b03c9f8432fe49538c3682bfcf4cf3	Vendor (CNA)
Linux Linux	0afc846bd80073ffcd2b8040f2b2fafaea3d9f72	Vendor (CNA)
Linux Linux	20756fec2f0108cb88e815941f1ffff88dc286fe	Vendor (CNA)
Linux Linux	3.16	Vendor (CNA)
Linux Linux	667f44f1392df6482483756458c48670e579e9ff	Vendor (CNA)
Linux Linux	929db734d12db41ca5f95424db4612397f1bd4a7	Vendor (CNA)
Linux Linux	9a38659a3d06080715691bd3139f9c4b61f688e3	Vendor (CNA)
Linux Linux	9a6d0db176f082685e0b6149700c0baf3ce2aa8b	Vendor (CNA)
Linux Linux	b1c6a8e554a39b222c0879a288ea98e338fc4d77	Vendor (CNA)
debian:linux	6.1.170-1 · Debian:12	Package registry (OSV)
suse:kernel-default	4.12.14-122.320.1 · SUSE:Linux Enterprise Live Patching 12 SP5	Package registry (OSV)
suse:kernel-source	4.12.14-122.320.1 · SUSE:Linux Enterprise Server 12 SP5-LTSS	Package registry (OSV)
suse:kernel-syms	4.12.14-122.320.1 · SUSE:Linux Enterprise Server 12 SP5-LTSS	Package registry (OSV)
suse:kgraft-patch-SLE12-SP5_Update_85	1-8.3.1 · SUSE:Linux Enterprise Live Patching 12 SP5	Package 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.

No history yet (it accumulates with the daily EPSS job).

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.

CVE-2026-3139228 days apartsmb: client: fix krb5 mount with username option
32Monitor

Chain candidates

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

CVE-2026-915555 days apartOS Command Injection in Rapid7 InsightConnect Sed Plugin via expression parameter.
35Monitor
CVE-2026-915355 days apartArbitrary File Read in Rapid7 InsightConnect Sed Plugin
26Monitor
CVE-2026-915455 days apartArbitrary File Write in Rapid7 InsightConnect Sed Plugin
26Monitor

Bug bounty scope

No known public program.

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

Technical details

Attack conditions

Someone on the same network segment 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: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Attack vector: Adjacent
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-287 · Improper Authentication

CVSS vector

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

nvd-secondary

Root cause

Authentication is added route by route instead of being enforced in one place. When a route added later bypasses the shared middleware, the session check never runs for it.

The bug in code

The whole CWE-287 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1app.use("/admin", requireSession, adminRouter);
2

3// Route added later skips the middleware
4app.post("/admin-api/config", updateConfig);

Fixed

1const admin = express.Router();
2admin.use(requireSession, requireRole("admin"));
3

4admin.post("/config", updateConfig);
5app.use("/admin", admin);

Attack context

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

Attack patterns (CAPEC)

ATT&CK techniques

Change log

SSVC exploitation— → noneOct 16, 2026, 5:07 PM UTC
Fix✗ → ✓Sep 28, 2026, 10:09 PM UTC

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

References

git.kernel.org/stable/c/061ee71ac6b03c9f8432fe49538c3682bfcf4cf3

Show all references (7 more)

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

All records