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NVD / CVE Program· CNA Linux

CVE-2025-38566: sunrpc: fix handling of server side tls alerts

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: 0.63% (FIRST EPSS); higher than 50.3% 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 25bb3647d30a20486b5fe7cff2b0e503c16c9692, 3b549da875414989f480b66835d514be80a0bd9c, 6b33c31cc788073bfbed9297e1f4486ed73d87da; azl3 kernel 6.6.96.2-2 on Azure Linux 3.0 6.6.104.2-1.
  • Severity is disputed: the assigning authority (CNA) scores it 9.8, NVD 7.5.

Low priority for now. Upgrade to Linux Linux 25bb3647d30a20486b5fe7cff2b0e503c16c9692, 3b549da875414989f480b66835d514be80a0bd9c, 6b33c31cc788073bfbed9297e1f4486ed73d87da; azl3 kernel 6.6.96.2-2 on Azure Linux 3.0 6.6.104.2-1 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: sunrpc: fix handling of server side tls alerts Scott Mayhew discovered a security exploit in NFS over TLS in tls_alert_recv() due to its assumption it can read data from the msg iterator's kvec.. kTLS implementation splits TLS non-data record payload between the control message buffer (which includes the type such as TLS aler or TLS cipher change) and the rest of the payload (say TLS alert's level/description) which goes into the msg payload buffer. This patch proposes to rework how control messages are setup and used by sock_recvmsg(). If no control message structure is setup, kTLS layer will read and process TLS data record types. As soon as it encounters a TLS control message, it would return an error. At that point, NFS can setup a kvec backed msg buffer and read in the control message such as a TLS alert. Msg iterator can advance the kvec pointer as a part of the copy process thus we need to revert the iterator before calling into the tls_alert_recv.

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Aug 19, 2025
Updated
Oct 15, 2026
EPSS
0.6% · 50th percentile

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
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
7.5
CNA · Linux
9.8
2.3 point gap

CVSS:3.1/AV:N/AC:L/PR:N/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-2025-38566

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

Affected versions

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

  • linux linux kernel6.4 and later · before 6.6.102
  • linux linux kernel6.7 and later · before 6.12.42
  • linux linux kernel6.13 and later · before 6.15.10
  • linux linux kernel6.16 and later · before 6.16.1
  • linux linux kernel6.17

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

    • 6.4affected
    • 5e052dda121e2870dd87181783da4a95d7d2927b and later · before b1df394621710b312f0393e3f240fdac0764f968affected · git
    • 5e052dda121e2870dd87181783da4a95d7d2927b and later · before 25bb3647d30a20486b5fe7cff2b0e503c16c9692affected · git
    • 5e052dda121e2870dd87181783da4a95d7d2927b and later · before 3b549da875414989f480b66835d514be80a0bd9caffected · git
    • 5e052dda121e2870dd87181783da4a95d7d2927b and later · before 6b33c31cc788073bfbed9297e1f4486ed73d87daaffected · git
    • 5e052dda121e2870dd87181783da4a95d7d2927b and later · before bee47cb026e762841f3faece47b51f985e215edbaffected · git
    • before 6.4not affected · semver
    • 6.6.102 and later · up to and including 6.6.*not affected · semver
    • 6.12.42 and later · up to and including 6.12.*not affected · semver
    • 6.15.10 and later · up to and including 6.15.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-55.34.1.el10_06.12.0-55.34.1.el10_0
AlmaLinux:10kernel-docbefore 6.12.0-55.34.1.el10_06.12.0-55.34.1.el10_0
AlmaLinux:9kernelbefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-64kbefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-64k-corebefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-64k-debugbefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-64k-debug-corebefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-64k-debug-develbefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-64k-debug-devel-matchedbefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-64k-debug-modulesbefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-64k-debug-modules-corebefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-64k-debug-modules-extrabefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-64k-develbefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-64k-devel-matchedbefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-64k-modulesbefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-64k-modules-corebefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-64k-modules-extrabefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-abi-stablelistsbefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-corebefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-cross-headersbefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-debugbefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-debug-corebefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-debug-develbefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6
AlmaLinux:9kernel-debug-devel-matchedbefore 5.14.0-570.55.1.el9_65.14.0-570.55.1.el9_6

+96

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-2025-38613Aug 19, 2025 · staging: gpib: fix unset padding field copy back to userspace
    22Monitor
  • ← EarlierCVE-2025-38560Aug 19, 2025 · x86/sev: Evict cache lines during SNP memory validation
    22Monitor
  • Later →CVE-2025-38571Aug 19, 2025 · sunrpc: fix client side handling of tls alerts
    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 Linux25bb3647d30a20486b5fe7cff2b0e503c16c9692Vendor (CNA)
Linux Linux3b549da875414989f480b66835d514be80a0bd9cVendor (CNA)
Linux Linux6b33c31cc788073bfbed9297e1f4486ed73d87daVendor (CNA)
Linux Linuxb1df394621710b312f0393e3f240fdac0764f968Vendor (CNA)
Linux Linuxbee47cb026e762841f3faece47b51f985e215edbVendor (CNA)
azl3 kernel 6.6.96.2-2 on Azure Linux 3.06.6.104.2-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
almalinux:kernel5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-core5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-core5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-core5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra5.14.0-570.55.1.el9_6 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-abi-stablelists6.12.0-55.34.1.el10_0 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-doc6.12.0-55.34.1.el10_0 · AlmaLinux:10Package registry (OSV)
debian:linux6.12.43-1 · Debian:13Package registry (OSV)
red hat:kernel-64k-debug-debuginfo0:6.12.0-55.34.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-64k-debug-devel0:6.12.0-55.34.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-64k-debug-devel-matched0:6.12.0-55.34.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-64k-debuginfo0:6.12.0-55.34.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-64k-devel0:6.12.0-55.34.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-64k-devel-matched0:6.12.0-55.34.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-debug-debuginfo0:6.12.0-55.34.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-debug-devel0:6.12.0-55.34.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-debug-devel-matched0:6.12.0-55.34.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-debuginfo0:6.12.0-55.34.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)
red hat:kernel-debuginfo-common-aarch640:6.12.0-55.34.1.el10_0 · Red Hat:enterprise_linux:10.0Package registry (OSV)

+14

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-2025-3968217 days aparttls: fix handling of zero-length records on the rx_listKEV
    70This week
  • CVE-2026-31637248 days apartrxrpc: reject undecryptable rxkad response tickets
    39Monitor
  • CVE-2026-31666248 days apartbtrfs: fix incorrect return value after changing leaf in lookup_extent_data_ref()
    31Monitor
  • CVE-2026-43133260 days apartKVM: nSVM: Always use vmcb01 in VMLOAD/VMSAVE emulation
    31Monitor
  • CVE-2024-47727302 days apartx86/tdx: Fix "in-kernel MMIO" check
    31Monitor
  • CVE-2026-63844334 days apartdrm/amdgpu/jpeg: set no_user_fence for JPEG v4.0.3 ring
    31Monitor

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

  • 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)

CWE-754 · Improper Check for Unusual or Exceptional Conditions

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/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 (4 more)

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

All records