KEVWire

Security intelligence, with context.

Response snapshot Oct 30, 2026, 17:36 UTC

Back to the wire
Permalink
VulnerabilityCVE-2026-52956

Linux kernel: libceph: Fix potential out-of-bounds access in __ceph_x_decrypt()

In the Linux kernel, the following vulnerability has been resolved: libceph: Fix potential out-of-bounds access in __ceph_x_decrypt() In __ceph_x_decrypt(), a part of the buffer p is interpreted as a ceph_x_encrypt_header, and the magic field of this struct is accessed.

At a glance

Exploited
Not known
Severity
7.5 High (CVSS 3.1)
Chance of exploitation
0.6% in the next 30 days
Sources
1 source

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-52956 (opens a new tab)

What happened

In the Linux kernel, the following vulnerability has been resolved:

libceph: Fix potential out-of-bounds access in __ceph_x_decrypt()

In __ceph_x_decrypt(), a part of the buffer p is interpreted as a ceph_x_encrypt_header, and the magic field of this struct is accessed. This happens without any guarantee that the buffer is large enough to hold this struct. The function parameter ciphertext_len represents the length of the ciphertext to decrypt and is guaranteed to be at most the remaining size of the allocated buffer p.

However, this value is not necessarily greater than sizeof(ceph_x_encrypt_header). E.g., a message frame of type FRAME_TAG_AUTH_REPLY_MORE, that is just as long to hold the ciphertext at its end with a ciphertext_len of 8 or less, can trigger an out-of-bounds memory access when accessing hdr->magic.

Continue reading

This patch fixes the issue by adding a check to ensure that the decrypted plaintext in the buffer is large enough to represent at least the ceph_x_encrypt_header.

Scores and how they were measured

CVSS base severity

7.5

Version 3.1As of

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

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

0.6%

Scored Percentile 50.2%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    NVD CVE-2026-52956 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  2. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  3. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  4. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  5. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-52956, scored 2026-10-30. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 30). Linux kernel: libceph: Fix potential out-of-bounds access in __ceph_x_decrypt() (CVE-2026-52956). https://kevwire.com/record/CVE-2026-52956

MLA

"Linux kernel: libceph: Fix potential out-of-bounds access in __ceph_x_decrypt() (CVE-2026-52956)." KEVWire, 30 Oct. 2026, kevwire.com/record/CVE-2026-52956.

Chicago

KEVWire. "Linux kernel: libceph: Fix potential out-of-bounds access in __ceph_x_decrypt() (CVE-2026-52956)." Last modified October 30, 2026. https://kevwire.com/record/CVE-2026-52956.

Evidence summary (plain text)

Linux kernel: libceph: Fix potential out-of-bounds access in __ceph_x_decrypt() (Jun 24, 2026).
In the Linux kernel, the following vulnerability has been resolved:

libceph: Fix potential out-of-bounds access in __ceph_x_decrypt()

In __ceph_x_decrypt(), a part of the buffer p is interpreted as a
ceph_x_encrypt_header, and the magic field of this struct is accessed.
This happens without any guarantee that the buffer is large enough to
hold this struct. The function parameter ciphertext_len represents the
length of the ciphertext to decrypt and is guaranteed to be at most the
remaining size of the allocated buffer p.
CVSS 7.5 (version 3.1; evidence as of Oct 30, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-52956).
EPSS 0.6% for the following 30 days, scored Oct 30, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-52956&date=2026-10-30).
Sources:
NVD CVE-2026-52956: https://nvd.nist.gov/vuln/detail/CVE-2026-52956
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-30T13:06:45.042Z&lastModEndDate=2026-10-30T14:50:57.069Z&resultsPerPage=500&startIndex=500
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-30T12:22:16.957Z&lastModEndDate=2026-10-30T14:05:57.373Z&resultsPerPage=500&startIndex=500
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-30T11:45:59.009Z&lastModEndDate=2026-10-30T13:20:57.281Z&resultsPerPage=500&startIndex=500
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-52956&date=2026-10-30
Record ID: CVE-2026-52956.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 30, 2026, 14:52 UTC. Ingestion is not an independent editorial investigation.

NVD status: Modified. Publication in the NVD is not evidence of exploitation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

Record JSON

Your account

Email alerts

Email alerts are coming as part of KEVWire Premium: join the waitlist. To follow your stack today, use its RSS feed, which honors your filters, or connect an AI agent through the API.

Suggest an improvement

Ideas, missing sources, corrections, and bugs are all welcome. No account needed. Suggestions are reviewed by a person before anything changes.

Record details

Record detail