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NVD / CVE Program· CNA canonical

CVE-2023-2640: On Ubuntu kernels carrying both c914c0e27eb0 and "UBUNTU: SAUCE: overlayfs: Skip permission checking for trusted.overlayfs.* xattrs", an unp

Noroxi assessment

Priority: Plan (action score 40/100)

  • A ready-made attack module is public (Metasploit, Nuclei); exploiting it takes no special expertise.
  • Because a ready-made attack tool exists, priority is at least “Plan”.
  • Probability of exploitation in the next 30 days: 15.1% (FIRST EPSS); higher than 96.7% of all records.
  • 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.
  • According to the record, no fixed version is available yet.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Add it to your regular patch cycle. Update when a fix is released; follow the vendor's advisory.

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

On Ubuntu kernels carrying both c914c0e27eb0 and "UBUNTU: SAUCE: overlayfs: Skip permission checking for trusted.overlayfs.* xattrs", an unprivileged user may set privileged extended attributes on the mounted files, leading them to be set on the upper files without the appropriate security checks.

HighCVSS 7.8 · v3.1—Weaponized No fix recorded
Published
Jul 25, 2023
Updated
Jun 17, 2026
EPSS
15.1% · 96th percentile

Report tools

JSON

Action score

40

Plan

Add it to your regular patch cycle.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
5 / 30 · 15.1%
Ready-made attack tool
4 / 40 · floor: at least 40

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
7.8
CNA · canonical
7.8
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
  • Weaponized exploit exists
  • No fixed version yet

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2023-2640

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
canonicalubuntu linux

Affected versions

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

  • canonical ubuntu linux23.04

Versions reported by the vendor

Affected version ranges reported by the assigning authority (canonical). Independent of NVD's CPE analysis and usually ahead of it.

  • Canonical Ubuntu Kernel

    • before 6.2.0-26.26not affected · semver
    • before 6.0.0-1020.20not affected · semver
    • before 5.4.0-155.172not affected · semver

Same product

canonical: all records

Other highest-scoring records for the same primary product.

  • CVE-2021-3493The overlayfs implementation in the linux kernel did not properly validate with respect to user namespaces the setting of file capabilities KEV
    76This week
  • CVE-2017-14492Heap-based buffer overflow in dnsmasq before 2.78 allows remote attackers to cause a denial of service (crash) or execute arbitrary code via
    67This week
  • CVE-2017-14493Stack-based buffer overflow in dnsmasq before 2.78 allows remote attackers to cause a denial of service (crash) or execute arbitrary code vi
    65This week

Published before and after this one in the same product

  • ← EarlierCVE-2020-11935Apr 6, 2023 · aufs: improperly managed inode reference counts in the vfsub_dentry_open() method
    22Monitor
  • ← EarlierCVE-2023-2612May 30, 2023 · shiftfs lock unbalance in Ubuntu-specific kernels
    18Monitor
  • Later →CVE-2023-32629Jul 25, 2023 · Local privilege escalation vulnerability in Ubuntu Kernels overlayfs ovl_copy_up_meta_inode_data skip permission checks when calling ovl_do_
    40Plan

Remediation

Which version to upgrade to

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

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

Weaponized

A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.

Evidence

  • Metasploit module ×1
  • Nuclei detection template ×1
  • Proof-of-concept repository on GitHub ×10

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Metasploit moduleexploit/linux/local/gameoverlay_privescGameOver(lay) Privilege Escalation and Container Escapeexploit2023-07-26
Nuclei detection templateNuclei template CVE-2023-2640 —
Proof-of-concept repository on GitHubstars:132023-08-15
Proof-of-concept repository on GitHubstars:172023-09-17
Proof-of-concept repository on GitHubstars:1372023-10-09
Proof-of-concept repository on GitHubstars:22023-11-02
Proof-of-concept repository on GitHubstars:12024-02-29
Proof-of-concept repository on GitHubstars:12024-03-19
Proof-of-concept repository on GitHubstars:12024-05-21
Proof-of-concept repository on GitHubstars:02026-04-04
Proof-of-concept repository on GitHubstars:02026-06-10
Proof-of-concept repository on GitHubstars:02026-07-22

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.

  1. Published
  2. Metasploitsame day
  3. First PoC+20 d
  4. TodayOct 29, 2026+1192 d
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.

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

  • 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
high · data or configuration can be modified
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
High
Availability impact
High

Weakness class (CWE)

CWE-863 · Incorrect Authorization

CVSS vector

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

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

Show all references (2 more)

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

All records