Vulnerability-Lookup

FKIE_CVE-2026-31705

Vulnerability from fkie_nvd - Published: 2026-05-01 14:16 - Updated: 2026-05-06 20:45

Severity ?

9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Summary

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment smb2_get_ea() applies 4-byte alignment padding via memset() after writing each EA entry. The bounds check on buf_free_len is performed before the value memcpy, but the alignment memset fires unconditionally afterward with no check on remaining space. When the EA value exactly fills the remaining buffer (buf_free_len == 0 after value subtraction), the alignment memset writes 1-3 NUL bytes past the buf_free_len boundary. In compound requests where the response buffer is shared across commands, the first command (e.g., READ) can consume most of the buffer, leaving a tight remainder for the QUERY_INFO EA response. The alignment memset then overwrites past the physical kvmalloc allocation into adjacent kernel heap memory. Add a bounds check before the alignment memset to ensure buf_free_len can accommodate the padding bytes. This is the same bug pattern fixed by commit beef2634f81f ("ksmbd: fix potencial OOB in get_file_all_info() for compound requests") and commit fda9522ed6af ("ksmbd: fix OOB write in QUERY_INFO for compound requests"), both of which added bounds checks before unconditional writes in QUERY_INFO response handlers.

References

URL	Tags
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/30010c952077a1c89ecdd71fc4d574c75a8f5617	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/790304c02bf9bd7b8171feda4294d6e62d32ae8f	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/922d48fe8c19f388ffa2f709f33acaae4e408de2	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/98f3de6ef4efbd899348d333f0902dc4ff14380c	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/ffbce350c6fd1e99116ea57383b9031717e36d3b	Patch

Impacted products

Vendor	Product	Version
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*

JSON

To clipboard

{
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  "descriptions": [
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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment\n\nsmb2_get_ea() applies 4-byte alignment padding via memset() after\nwriting each EA entry. The bounds check on buf_free_len is performed\nbefore the value memcpy, but the alignment memset fires unconditionally\nafterward with no check on remaining space.\n\nWhen the EA value exactly fills the remaining buffer (buf_free_len == 0\nafter value subtraction), the alignment memset writes 1-3 NUL bytes\npast the buf_free_len boundary. In compound requests where the response\nbuffer is shared across commands, the first command (e.g., READ) can\nconsume most of the buffer, leaving a tight remainder for the QUERY_INFO\nEA response. The alignment memset then overwrites past the physical\nkvmalloc allocation into adjacent kernel heap memory.\n\nAdd a bounds check before the alignment memset to ensure buf_free_len\ncan accommodate the padding bytes.\n\nThis is the same bug pattern fixed by commit beef2634f81f (\"ksmbd: fix\npotencial OOB in get_file_all_info() for compound requests\") and\ncommit fda9522ed6af (\"ksmbd: fix OOB write in QUERY_INFO for compound\nrequests\"), both of which added bounds checks before unconditional\nwrites in QUERY_INFO response handlers."
    }
  ],
  "id": "CVE-2026-31705",
  "lastModified": "2026-05-06T20:45:44.287",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
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        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
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  "published": "2026-05-01T14:16:20.473",
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    },
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  "vulnStatus": "Analyzed",
  "weaknesses": [
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          "lang": "en",
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      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}

CVE-2026-31705 (GCVE-0-2026-31705)

Vulnerability from cvelistv5 – Published: 2026-05-01 13:56 – Updated: 2026-05-03 05:45

Title

ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment

Summary

Severity ?

9.8 (Critical)


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

Assigner

Linux

References

URL

Tags

	https://git.kernel.org/stable/c/ffbce350c6fd1e991…
	https://git.kernel.org/stable/c/98f3de6ef4efbd899…
	https://git.kernel.org/stable/c/790304c02bf9bd7b8…
	https://git.kernel.org/stable/c/922d48fe8c19f388f…
	https://git.kernel.org/stable/c/30010c952077a1c89…

Impacted products

Vendor

Product

Version

Linux

Affected: e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d , < ffbce350c6fd1e99116ea57383b9031717e36d3b (git)
Affected: e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d , < 98f3de6ef4efbd899348d333f0902dc4ff14380c (git)
Affected: e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d , < 790304c02bf9bd7b8171feda4294d6e62d32ae8f (git)
Affected: e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d , < 922d48fe8c19f388ffa2f709f33acaae4e408de2 (git)
Affected: e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d , < 30010c952077a1c89ecdd71fc4d574c75a8f5617 (git)
Affected: f2283680a80571ca82d710bc6ecd8f8beac67d63 (git)
Affected: 9f297df20d93411c0b4ddad7f88ba04a7cd36e77 (git)

Linux

Affected: 6.6
Unaffected: 0 , < 6.6 (semver)
Unaffected: 6.6.136 , ≤ 6.6.* (semver)
Unaffected: 6.12.84 , ≤ 6.12.* (semver)
Unaffected: 6.18.25 , ≤ 6.18.* (semver)
Unaffected: 7.0.2 , ≤ 7.0.* (semver)
Unaffected: 7.1-rc1 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

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          "programFiles": [
            "fs/smb/server/smb2pdu.c"
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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

FKIE_CVE-2026-31705

CVE-2026-31705 (GCVE-0-2026-31705)

Tags

Sightings

Nomenclature