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NVD / CVE Program· CNA Linux

CVE-2026-46033: crypto: authencesn - reject short ahash digests during instance creation

Noroxi assessment

Priority: Monitor (action score 28/100)

  • 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: 0.13% (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 2f31cd1e64a079c845bca31d2da7b3c90a311726, 5db6ef9847717329f12c5ea8aba7e9f588a980c0, 67f1f0933cc3d78dde222842bcad2778ec7a0b88; azl3 kernel 6.6.139.1-1 on Azure Linux 3.0 6.6.141.1-1.

Low priority for now. Upgrade to Linux Linux 2f31cd1e64a079c845bca31d2da7b3c90a311726, 5db6ef9847717329f12c5ea8aba7e9f588a980c0, 67f1f0933cc3d78dde222842bcad2778ec7a0b88; azl3 kernel 6.6.139.1-1 on Azure Linux 3.0 6.6.141.1-1 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: crypto: authencesn - reject short ahash digests during instance creation authencesn requires either a zero authsize or an authsize of at least 4 bytes because the ESN encrypt/decrypt paths always move 4 bytes of high-order sequence number data at the end of the authenticated data. While crypto_authenc_esn_setauthsize() already rejects explicit non-zero authsizes in the range 1..3, crypto_authenc_esn_create() still copied auth->digestsize into inst->alg.maxauthsize without validating it. The AEAD core then initialized the tfm's default authsize from that value. As a result, selecting an ahash with digest size 1..3, such as cbcmac(cipher_null), exposed authencesn instances whose default authsize was invalid even though setauthsize() would have rejected the same value. AF_ALG could then trigger the ESN tail handling with a too-short tag and hit an out-of-bounds access. Reject authencesn instances whose ahash digest size is in the invalid non-zero range 1..3 so that no tfm can inherit an unsupported default authsize.

HighCVSS 7.1 · v3.1—No exploit Fix available
Published
May 27, 2026
Updated
Oct 15, 2026
EPSS
0.1% · 3th percentile

Report tools

JSON

Action score

28

Monitor

Low priority for now.

CVSS
28 / 40 · 7.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CNA vs NVD score

NVD
7.1
CNA · Linux
7.1
agree

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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When you'll hear from us

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  • when exploit code appears or is weaponized
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  • 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 kernel4.11 and later · before 5.10.258
  • linux linux kernel5.11 and later · before 5.15.209
  • linux linux kernel5.16 and later · before 6.1.175
  • linux linux kernel6.2 and later · before 6.6.140
  • linux linux kernel6.7 and later · before 6.12.86
  • linux linux kernel6.13 and later · before 6.18.27
  • linux linux kernel6.19 and later · before 7.0.4
  • linux linux kernel7.1

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

    • 4.11affected
    • f15f05b0a5de667c821a9727c33bce9d1d9b26dd and later · before 77f59fb2d3aa33e90ec6cbbf45dcfb20ab82b1a9affected · git
    • f15f05b0a5de667c821a9727c33bce9d1d9b26dd and later · before 2f31cd1e64a079c845bca31d2da7b3c90a311726affected · git
    • f15f05b0a5de667c821a9727c33bce9d1d9b26dd and later · before d4c6a6d08e70bb1083c7c405fc7faacbf19aebc0affected · git
    • f15f05b0a5de667c821a9727c33bce9d1d9b26dd and later · before b69933e97efea238ebbfcf70c2b1be1cd03f13e3affected · git
    • f15f05b0a5de667c821a9727c33bce9d1d9b26dd and later · before 67f1f0933cc3d78dde222842bcad2778ec7a0b88affected · git
    • f15f05b0a5de667c821a9727c33bce9d1d9b26dd and later · before b42821c15445f93daea3e76ada682b2b7181c476affected · git
    • f15f05b0a5de667c821a9727c33bce9d1d9b26dd and later · before 9aff81e8217e9de2929084b03b3c7f81988c112baffected · git
    • f15f05b0a5de667c821a9727c33bce9d1d9b26dd and later · before 5db6ef9847717329f12c5ea8aba7e9f588a980c0affected · git
    • before 4.11not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.176-16.1.176-1
Debian:13linuxbefore 6.12.86-16.12.86-1
Debian:14linuxbefore 7.0.4-17.0.4-1

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-2026-46027May 27, 2026 · net/smc: avoid early lgr access in smc_clc_wait_msg
    30Monitor
  • ← EarlierCVE-2026-46032May 27, 2026 · KVM: nSVM: Triple fault if restore host CR3 fails on nested #VMEXIT
    22Monitor
  • Later →CVE-2026-46037May 27, 2026 · ipv4: icmp: validate reply type before using icmp_pointers
    32Monitor

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 Linux2f31cd1e64a079c845bca31d2da7b3c90a311726Vendor (CNA)
Linux Linux5db6ef9847717329f12c5ea8aba7e9f588a980c0Vendor (CNA)
Linux Linux67f1f0933cc3d78dde222842bcad2778ec7a0b88Vendor (CNA)
Linux Linux77f59fb2d3aa33e90ec6cbbf45dcfb20ab82b1a9Vendor (CNA)
Linux Linux9aff81e8217e9de2929084b03b3c7f81988c112bVendor (CNA)
Linux Linuxb42821c15445f93daea3e76ada682b2b7181c476Vendor (CNA)
Linux Linuxb69933e97efea238ebbfcf70c2b1be1cd03f13e3Vendor (CNA)
Linux Linuxd4c6a6d08e70bb1083c7c405fc7faacbf19aebc0Vendor (CNA)
azl3 kernel 6.6.139.1-1 on Azure Linux 3.06.6.141.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.176-1 · 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

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).

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
none
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
None
Availability impact
High

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

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

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

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

References

Show all references (13 more)

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

All records