Vulnerability-Lookup

GHSA-X8VP-V84J-H4HG

Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-14 15:32

Details

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

ecryptfs: reject too-small tag 70 packets

ecryptfs_parse_tag_70_packet() subtracts fixed metadata fields from the parsed packet body size to derive the encrypted filename size. A malformed packet with a body smaller than those fixed fields can underflow that size calculation.

Reject tag 70 packets before the subtraction unless the body contains the signature, cipher code, and at least one byte of encrypted filename data.

Severity

7.8 (High)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-89606"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-11T20:19:45Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\necryptfs: reject too-small tag 70 packets\n\necryptfs_parse_tag_70_packet() subtracts fixed metadata fields from the\nparsed packet body size to derive the encrypted filename size.  A\nmalformed packet with a body smaller than those fixed fields can underflow\nthat size calculation.\n\nReject tag 70 packets before the subtraction unless the body contains the\nsignature, cipher code, and at least one byte of encrypted filename data.",
  "id": "GHSA-x8vp-v84j-h4hg",
  "modified": "2026-09-14T15:32:31Z",
  "published": "2026-09-11T21:31:33Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89606"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2e5afed9503dd1d85004c09503adc2cb584c0188"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/414a0f04feb06f03523edf7e2a8be1d7f1a9b160"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5668121974eb7f7aa82793a9d0d13abadb8904dc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9d88391bbed76eb091cddd50b0af87b1c6f22589"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b31da1ecf13929a8d7f8d2727843d2fe35396b75"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d2869768eab5648e6edc05f47e0716e5328e6681"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/df5f375a6151ef71f636da044bcef90c26697255"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e97bbe1b2bd82ec2ae37ad2e4965b4d3e78bbf7f"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-89606 (GCVE-0-2026-89606)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:45 – Updated: 2026-09-14 12:01

Title

ecryptfs: reject too-small tag 70 packets

Summary

In the Linux kernel, the following vulnerability has been resolved: ecryptfs: reject too-small tag 70 packets ecryptfs_parse_tag_70_packet() subtracts fixed metadata fields from the parsed packet body size to derive the encrypted filename size. A malformed packet with a body smaller than those fixed fields can underflow that size calculation. Reject tag 70 packets before the subtraction unless the body contains the signature, cipher code, and at least one byte of encrypted filename data.

Severity

7.8 (High)


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

Assigner

Linux mitre root

References

8 references

URL	Tags
https://git.kernel.org/stable/c/df5f375a6151ef71f…
https://git.kernel.org/stable/c/5668121974eb7f7aa…
https://git.kernel.org/stable/c/2e5afed9503dd1d85…
https://git.kernel.org/stable/c/414a0f04feb06f035…
https://git.kernel.org/stable/c/9d88391bbed76eb09…
https://git.kernel.org/stable/c/b31da1ecf13929a8d…
https://git.kernel.org/stable/c/d2869768eab5648e6…
https://git.kernel.org/stable/c/e97bbe1b2bd82ec2a…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 9c79f34f7ee71cd28272332b424ca64b2be006ab , < df5f375a6151ef71f636da044bcef90c26697255 (git) Affected: 9c79f34f7ee71cd28272332b424ca64b2be006ab , < 5668121974eb7f7aa82793a9d0d13abadb8904dc (git) Affected: 9c79f34f7ee71cd28272332b424ca64b2be006ab , < 2e5afed9503dd1d85004c09503adc2cb584c0188 (git) Affected: 9c79f34f7ee71cd28272332b424ca64b2be006ab , < 414a0f04feb06f03523edf7e2a8be1d7f1a9b160 (git) Affected: 9c79f34f7ee71cd28272332b424ca64b2be006ab , < 9d88391bbed76eb091cddd50b0af87b1c6f22589 (git) Affected: 9c79f34f7ee71cd28272332b424ca64b2be006ab , < b31da1ecf13929a8d7f8d2727843d2fe35396b75 (git) Affected: 9c79f34f7ee71cd28272332b424ca64b2be006ab , < d2869768eab5648e6edc05f47e0716e5328e6681 (git) Affected: 9c79f34f7ee71cd28272332b424ca64b2be006ab , < e97bbe1b2bd82ec2ae37ad2e4965b4d3e78bbf7f (git)
Linux	Linux	Affected: 2.6.29 Unaffected: 0 , < 2.6.29 (semver) Unaffected: 5.10.270 , ≤ 5.10.* (semver) Unaffected: 5.15.221 , ≤ 5.15.* (semver) Unaffected: 6.1.188 , ≤ 6.1.* (semver) Unaffected: 6.6.157 , ≤ 6.6.* (semver) Unaffected: 6.12.109 , ≤ 6.12.* (semver) Unaffected: 6.18.50 , ≤ 6.18.* (semver) Unaffected: 7.2.4 , ≤ 7.2.* (semver) Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ecryptfs/keystore.c"
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              "version": "0",
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              "versionType": "semver"
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              "versionType": "semver"
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              "lessThanOrEqual": "*",
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\necryptfs: reject too-small tag 70 packets\n\necryptfs_parse_tag_70_packet() subtracts fixed metadata fields from the\nparsed packet body size to derive the encrypted filename size.  A\nmalformed packet with a body smaller than those fixed fields can underflow\nthat size calculation.\n\nReject tag 70 packets before the subtraction unless the body contains the\nsignature, cipher code, and at least one byte of encrypted filename data."
        }
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            "baseSeverity": "HIGH",
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            "version": "3.1"
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            {
              "lang": "en",
              "value": "AV:L - The bug is reached only through local VFS operations on an eCryptfs mount with filename encryption: getdents via ecryptfs_filldir() and readlink via ecryptfs_get_link(), which decode lower-filesystem names or symlink targets into tag 70 packets. No network protocol or remote peer data is parsed.\nAC:L - An attacker who can create names on the lower filesystem fully controls the tag-70 length byte and can copy a valid FNEK signature from their own mount or existing encrypted names, so the unsigned size wrap is deterministic with no race or uninfluenced condition.\nPR:L - Unprivileged users reach this on standard eCryptfs deployments (encrypted home/Private via setuid mount.ecryptfs_private, or an already-mounted per-user eCryptfs directory) by writing the lower directory they own; triggering does not require init-namespace root.\nUI:N - The attacker plants the malformed ECRYPTFS_FNEK_ENCRYPTED name or lower symlink target and then issues getdents or readlink on their own eCryptfs mount; no separate victim action is required, and in the encrypted-home case the mount already exists at login.\nS:U - Memory corruption and oops stay inside the host kernel\u0027s eCryptfs/VFS context. This is ordinary kernel impact, not a VM, IOMMU, or sandbox-boundary escape.\nC:H - The underflowed block_aligned_filename_size is used as the scatterlist, kmalloc, and skcipher-decrypt length for the encrypted filename, so a wrapped length becomes an out-of-bounds read of kernel memory adjacent to the decoded packet buffer.\nI:H - The same wrapped length is the destination size for kmalloc plus crypto_skcipher_decrypt and the subsequent memcpy of the decrypted name, yielding an out-of-bounds write into heap/crypto scratch buffers that can be used for control-flow hijack.\nA:H - virt_to_scatterlist() returns 0 for the wrapped size without the caller setting rc, so parse_tag_70_packet() returns success with a NULL filename; ecryptfs_get_link() then does buf[len]=\u0027\\0\u0027 on that NULL pointer and oopses the kernel."
            }
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        }
      ],
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        "dateUpdated": "2026-09-14T12:01:26.751Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/e97bbe1b2bd82ec2ae37ad2e4965b4d3e78bbf7f"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89606",
    "datePublished": "2026-09-11T19:45:08.832Z",
    "dateReserved": "2026-09-11T19:38:34.733Z",
    "dateUpdated": "2026-09-14T12:01:26.751Z",
    "state": "PUBLISHED"
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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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

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