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NVD / CVE Program· CNA Linux

CVE-2025-37756: net: tls: explicitly disallow disconnect

Noroxi assessment

Priority: Monitor (action score 22/100)

  • 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: 0.30% (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 2bcad8fefcecdd5f005d8c550b25d703c063c34a, 5071a1e606b30c0c11278d3c6620cd6a24724cf6, 7bdcf5bc35ae59fc4a0fa23276e84b4d1534a3cf; azl3 kernel 6.6.85.1-4 on Azure Linux 3.0 6.6.92.2-1; azl3 kernel 6.6.92.2-1 on Azure Linux 3.0 6.6.92.2-1.
  • Severity is disputed: the assigning authority (CNA) scores it 7.8, NVD 5.5.

Low priority for now. Upgrade to Linux Linux 2bcad8fefcecdd5f005d8c550b25d703c063c34a, 5071a1e606b30c0c11278d3c6620cd6a24724cf6, 7bdcf5bc35ae59fc4a0fa23276e84b4d1534a3cf; azl3 kernel 6.6.85.1-4 on Azure Linux 3.0 6.6.92.2-1; azl3 kernel 6.6.92.2-1 on Azure Linux 3.0 6.6.92.2-1 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: net: tls: explicitly disallow disconnect syzbot discovered that it can disconnect a TLS socket and then run into all sort of unexpected corner cases. I have a vague recollection of Eric pointing this out to us a long time ago. Supporting disconnect is really hard, for one thing if offload is enabled we'd need to wait for all packets to be _acked_. Disconnect is not commonly used, disallow it. The immediate problem syzbot run into is the warning in the strp, but that's just the easiest bug to trigger: WARNING: CPU: 0 PID: 5834 at net/tls/tls_strp.c:486 tls_strp_msg_load+0x72e/0xa80 net/tls/tls_strp.c:486 RIP: 0010:tls_strp_msg_load+0x72e/0xa80 net/tls/tls_strp.c:486 Call Trace: <TASK> tls_rx_rec_wait+0x280/0xa60 net/tls/tls_sw.c:1363 tls_sw_recvmsg+0x85c/0x1c30 net/tls/tls_sw.c:2043 inet6_recvmsg+0x2c9/0x730 net/ipv6/af_inet6.c:678 sock_recvmsg_nosec net/socket.c:1023 [inline] sock_recvmsg+0x109/0x280 net/socket.c:1045 __sys_recvfrom+0x202/0x380 net/socket.c:2237

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
May 1, 2025
Updated
Oct 15, 2026
EPSS
0.3% · 22th percentile
CWE
—

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
5.5
CNA · Linux
7.8
2.3 point gap

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

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-2025-37756

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.

VendorProduct
linuxlinux kernel
debiandebian linux

Affected versions

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

  • debian debian linux11.0
  • linux linux kernel5.11 and later · before 5.15.181
  • linux linux kernel5.16 and later · before 6.1.135
  • linux linux kernel6.2 and later · before 6.6.88
  • linux linux kernel4.13 and later · before 5.10.237
  • linux linux kernel6.13 and later · before 6.13.12
  • linux linux kernel6.14 and later · before 6.14.3
  • linux linux kernel6.7 and later · before 6.12.24
  • linux linux kernel6.15

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

    • 4.13affected
    • 3c4d7559159bfe1e3b94df3a657b2cda3a34e218 and later · before 7bdcf5bc35ae59fc4a0fa23276e84b4d1534a3cfaffected · git
    • 3c4d7559159bfe1e3b94df3a657b2cda3a34e218 and later · before ac91c6125468be720eafde9c973994cb45b61d44affected · git
    • 3c4d7559159bfe1e3b94df3a657b2cda3a34e218 and later · before f3ce4d3f874ab7919edca364c147ac735f9f1d04affected · git
    • 3c4d7559159bfe1e3b94df3a657b2cda3a34e218 and later · before 2bcad8fefcecdd5f005d8c550b25d703c063c34aaffected · git
    • 3c4d7559159bfe1e3b94df3a657b2cda3a34e218 and later · before 9fcbca0f801580cbb583e9cb274e2c7fbe766ca6affected · git
    • 3c4d7559159bfe1e3b94df3a657b2cda3a34e218 and later · before c665bef891e8972e1d3ce5bbc0d42a373346a2c3affected · git
    • 3c4d7559159bfe1e3b94df3a657b2cda3a34e218 and later · before 8513411ec321942bd3cfed53d5bb700665c67d86affected · git
    • 3c4d7559159bfe1e3b94df3a657b2cda3a34e218 and later · before 5071a1e606b30c0c11278d3c6620cd6a24724cf6affected · git
    • before 4.13not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.135-16.1.135-1
Debian:13linuxbefore 6.12.25-16.12.25-1
SUSE:Linux Micro 6.1kernel-defaultbefore 6.4.0-31.16.4.0-31.1
SUSE:Linux Micro 6.1kernel-default-basebefore 6.4.0-31.1.21.96.4.0-31.1.21.9
SUSE:Linux Micro 6.1kernel-kvmsmallbefore 6.4.0-31.16.4.0-31.1
SUSE:Linux Micro 6.1kernel-rtbefore 6.4.0-34.16.4.0-34.1
SUSE:Linux Micro 6.1kernel-sourcebefore 6.4.0-31.16.4.0-31.1
SUSE:Linux Micro 6.1kernel-source-rtbefore 6.4.0-34.16.4.0-34.1

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
    90Now
  • 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
    89Now
  • 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-2025-37747May 1, 2025 · perf: Fix hang while freeing sigtrap event
    22Monitor
  • ← EarlierCVE-2025-37750May 1, 2025 · smb: client: fix UAF in decryption with multichannel
    31Monitor
  • Later →CVE-2025-37757May 1, 2025 · tipc: fix memory leak in tipc_link_xmit
    22Monitor

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 Linux2bcad8fefcecdd5f005d8c550b25d703c063c34aVendor (CNA)
Linux Linux5071a1e606b30c0c11278d3c6620cd6a24724cf6Vendor (CNA)
Linux Linux7bdcf5bc35ae59fc4a0fa23276e84b4d1534a3cfVendor (CNA)
Linux Linux8513411ec321942bd3cfed53d5bb700665c67d86Vendor (CNA)
Linux Linux9fcbca0f801580cbb583e9cb274e2c7fbe766ca6Vendor (CNA)
Linux Linuxac91c6125468be720eafde9c973994cb45b61d44Vendor (CNA)
Linux Linuxc665bef891e8972e1d3ce5bbc0d42a373346a2c3Vendor (CNA)
Linux Linuxf3ce4d3f874ab7919edca364c147ac735f9f1d04Vendor (CNA)
azl3 kernel 6.6.85.1-4 on Azure Linux 3.06.6.92.2-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 kernel 6.6.92.2-1 on Azure Linux 3.06.6.92.2-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.135-1 · Debian:12Package registry (OSV)
suse:kernel-default6.4.0-31.1 · SUSE:Linux Micro 6.1Package registry (OSV)
suse:kernel-default-base6.4.0-31.1.21.9 · SUSE:Linux Micro 6.1Package registry (OSV)
suse:kernel-kvmsmall6.4.0-31.1 · SUSE:Linux Micro 6.1Package registry (OSV)
suse:kernel-rt6.4.0-34.1 · SUSE:Linux Micro 6.1Package registry (OSV)
suse:kernel-source6.4.0-31.1 · SUSE:Linux Micro 6.1Package registry (OSV)
suse:kernel-source-rt6.4.0-34.1 · SUSE:Linux Micro 6.1Package 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.

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).

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

Weakness class (CWE)

—

CVSS vector

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

nvd-primary

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 (10 more)

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

All records