CVE-2026-98969 (GCVE-0-2026-98969)

Vulnerability from cvelistv5 – Published: 2026-10-23 12:19 – Updated: 2026-10-23 12:19
VLAI
Title
net/sched: em_text: reject unterminated algo before autoload
Summary
In the Linux kernel, the following vulnerability has been resolved: net/sched: em_text: reject unterminated algo before autoload This is a follow-up to commit 9c572a83037a ("net/sched: fix potential stack infoleak in em_text_dump()"), which zero-initialised the dump-side struct. Sashiko pointed at a pre-existing bug that exposed the change-side input-validation gap open. em_text_change() casts the raw netlink attribute payload to struct tcf_em_text and passes conf->algo, a 16-byte array with no enforced NUL terminator, to textsearch_prepare(). On the TS_AUTOLOAD retry textsearch_prepare() calls request_module("ts_%s", algo); vsnprintf() walks %s until it finds a NUL, so an algo[] with no NUL reads past the array into the adjacent struct fields and payload and feeds those bytes to the usermode helper command line. This is an out-of-bounds read and a kernel memory disclosure. Reject the attribute when no NUL exists within TC_EM_TEXT_ALGOSIZ bytes, matching the check xt_string has had since 3ab720881b6e. Conditions to recreate the bug: - CAP_NET_ADMIN on the target netns (namespace-local via unshare -Urn is enough) - install clsact on an interface, then add a basic filter with one text ematch whose algo[] is 16 bytes with no NUL (e.g. "A"*16) and pattern_len at least 1 - the add fails with -ENOENT and the kernel invokes modprobe with a module name made of "ts_" plus the 16 bytes and the adjacent payload
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7061 records in the last 180 days details
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: d675c989ed2d4ba23dff615330b04371aea83534 , < 00bcc303000bac524d62eed054d77372b38ace0f (git)
Affected: d675c989ed2d4ba23dff615330b04371aea83534 , < 22182f91c6703af6e9832cffe6d22b381031cb5a (git)
Affected: d675c989ed2d4ba23dff615330b04371aea83534 , < 85e5512369d4fe6e5f2c43712d9f9e01d4ae8437 (git)
Affected: d675c989ed2d4ba23dff615330b04371aea83534 , < b627c6ba20be20334338229b4820baacb9d96826 (git)
Affected: d675c989ed2d4ba23dff615330b04371aea83534 , < c9728fcf2e7fb4a7a8d08ebd9524c3b02ae1a021 (git)
guessed Create a notification for this product.
Linux Linux Affected: 2.6.13
Unaffected: 0 , < 2.6.13 (semver)
Unaffected: 6.6.160 , ≤ 6.6.* (semver)
Unaffected: 6.12.113 , ≤ 6.12.* (semver)
Unaffected: 6.18.57 , ≤ 6.18.* (semver)
Unaffected: 7.2.11 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website

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          "programFiles": [
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      "cpeApplicability": [
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: em_text: reject unterminated algo before autoload\n\nThis is a follow-up to commit 9c572a83037a (\"net/sched: fix potential\nstack infoleak in em_text_dump()\"), which zero-initialised the dump-side\nstruct. Sashiko pointed at a pre-existing bug that exposed the change-side\ninput-validation gap open.\n\nem_text_change() casts the raw netlink attribute payload to struct\ntcf_em_text and passes conf-\u003ealgo, a 16-byte array with no enforced NUL\nterminator, to textsearch_prepare().  On the TS_AUTOLOAD retry\ntextsearch_prepare() calls request_module(\"ts_%s\", algo); vsnprintf()\nwalks %s until it finds a NUL, so an algo[] with no NUL reads past the\narray into the adjacent struct fields and payload and feeds those bytes\nto the usermode helper command line.  This is an out-of-bounds read and\na kernel memory disclosure.\n\nReject the attribute when no NUL exists within TC_EM_TEXT_ALGOSIZ bytes,\nmatching the check xt_string has had since 3ab720881b6e.\n\nConditions to recreate the bug:\n- CAP_NET_ADMIN on the target netns (namespace-local via unshare -Urn\n  is enough)\n- install clsact on an interface, then add a basic filter with one text\n  ematch whose algo[] is 16 bytes with no NUL (e.g. \"A\"*16) and\n  pattern_len at least 1\n- the add fails with -ENOENT and the kernel invokes modprobe with a\n  module name made of \"ts_\" plus the 16 bytes and the adjacent payload"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-23T12:19:42.012Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/00bcc303000bac524d62eed054d77372b38ace0f"
        },
        {
          "url": "https://git.kernel.org/stable/c/22182f91c6703af6e9832cffe6d22b381031cb5a"
        },
        {
          "url": "https://git.kernel.org/stable/c/85e5512369d4fe6e5f2c43712d9f9e01d4ae8437"
        },
        {
          "url": "https://git.kernel.org/stable/c/b627c6ba20be20334338229b4820baacb9d96826"
        },
        {
          "url": "https://git.kernel.org/stable/c/c9728fcf2e7fb4a7a8d08ebd9524c3b02ae1a021"
        }
      ],
      "title": "net/sched: em_text: reject unterminated algo before autoload",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98969",
    "datePublished": "2026-10-23T12:19:42.012Z",
    "dateReserved": "2026-09-25T10:25:14.383Z",
    "dateUpdated": "2026-10-23T12:19:42.012Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
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      "current_release_date": "2026-10-24T01:10:21.000Z",
      "cve": "CVE-2026-98969",
      "id": "msrc_CVE-2026-98969",
      "initial_release_date": "2026-10-24T01:10:21.000Z",
      "product_status:under_investigation": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "net/sched: em_text: reject unterminated algo before autoload",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-98969.json",
      "version": "1"
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            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: em_text: reject unterminated algo before autoload\n\nThis is a follow-up to commit 9c572a83037a (\"net/sched: fix potential\nstack infoleak in em_text_dump()\"), which zero-initialised the dump-side\nstruct. Sashiko pointed at a pre-existing bug that exposed the change-side\ninput-validation gap open.\n\nem_text_change() casts the raw netlink attribute payload to struct\ntcf_em_text and passes conf-\u003ealgo, a 16-byte array with no enforced NUL\nterminator, to textsearch_prepare().  On the TS_AUTOLOAD retry\ntextsearch_prepare() calls request_module(\"ts_%s\", algo); vsnprintf()\nwalks %s until it finds a NUL, so an algo[] with no NUL reads past the\narray into the adjacent struct fields and payload and feeds those bytes\nto the usermode helper command line.  This is an out-of-bounds read and\na kernel memory disclosure.\n\nReject the attribute when no NUL exists within TC_EM_TEXT_ALGOSIZ bytes,\nmatching the check xt_string has had since 3ab720881b6e.\n\nConditions to recreate the bug:\n- CAP_NET_ADMIN on the target netns (namespace-local via unshare -Urn\n  is enough)\n- install clsact on an interface, then add a basic filter with one text\n  ematch whose algo[] is 16 bytes with no NUL (e.g. \"A\"*16) and\n  pattern_len at least 1\n- the add fails with -ENOENT and the kernel invokes modprobe with a\n  module name made of \"ts_\" plus the 16 bytes and the adjacent payload"
          }
        ],
        "id": "CVE-2026-98969",
        "lastModified": "2026-10-23T13:17:18.440",
        "metrics": {},
        "published": "2026-10-23T13:17:18.440",
        "references": [
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    }
  }
}



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