CVE-2025-37814 (GCVE-0-2025-37814)
Vulnerability from cvelistv5
Published
2025-05-08 06:26
Modified
2026-08-05 11:57
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: tty: Require CAP_SYS_ADMIN for all usages of TIOCL_SELMOUSEREPORT This requirement was overeagerly loosened in commit 2f83e38a095f ("tty: Permit some TIOCL_SETSEL modes without CAP_SYS_ADMIN"), but as it turns out, (1) the logic I implemented there was inconsistent (apologies!), (2) TIOCL_SELMOUSEREPORT might actually be a small security risk after all, and (3) TIOCL_SELMOUSEREPORT is only meant to be used by the mouse daemon (GPM or Consolation), which runs as CAP_SYS_ADMIN already. In more detail: 1. The previous patch has inconsistent logic: In commit 2f83e38a095f ("tty: Permit some TIOCL_SETSEL modes without CAP_SYS_ADMIN"), we checked for sel_mode == TIOCL_SELMOUSEREPORT, but overlooked that the lower four bits of this "mode" parameter were actually used as an additional way to pass an argument. So the patch did actually still require CAP_SYS_ADMIN, if any of the mouse button bits are set, but did not require it if none of the mouse buttons bits are set. This logic is inconsistent and was not intentional. We should have the same policies for using TIOCL_SELMOUSEREPORT independent of the value of the "hidden" mouse button argument. I sent a separate documentation patch to the man page list with more details on TIOCL_SELMOUSEREPORT: https://lore.kernel.org/all/20250223091342.35523-2-gnoack3000@gmail.com/ 2. TIOCL_SELMOUSEREPORT is indeed a potential security risk which can let an attacker simulate "keyboard" input to command line applications on the same terminal, like TIOCSTI and some other TIOCLINUX "selection mode" IOCTLs. By enabling mouse reporting on a terminal and then injecting mouse reports through TIOCL_SELMOUSEREPORT, an attacker can simulate mouse movements on the same terminal, similar to the TIOCSTI keystroke injection attacks that were previously possible with TIOCSTI and other TIOCL_SETSEL selection modes. Many programs (including libreadline/bash) are then prone to misinterpret these mouse reports as normal keyboard input because they do not expect input in the X11 mouse protocol form. The attacker does not have complete control over the escape sequence, but they can at least control the values of two consecutive bytes in the binary mouse reporting escape sequence. I went into more detail on that in the discussion at https://lore.kernel.org/all/20250221.0a947528d8f3@gnoack.org/ It is not equally trivial to simulate arbitrary keystrokes as it was with TIOCSTI (commit 83efeeeb3d04 ("tty: Allow TIOCSTI to be disabled")), but the general mechanism is there, and together with the small number of existing legit use cases (see below), it would be better to revert back to requiring CAP_SYS_ADMIN for TIOCL_SELMOUSEREPORT, as it was already the case before commit 2f83e38a095f ("tty: Permit some TIOCL_SETSEL modes without CAP_SYS_ADMIN"). 3. TIOCL_SELMOUSEREPORT is only used by the mouse daemons (GPM or Consolation), and they are the only legit use case: To quote console_codes(4): The mouse tracking facility is intended to return xterm(1)-compatible mouse status reports. Because the console driver has no way to know the device or type of the mouse, these reports are returned in the console input stream only when the virtual terminal driver receives a mouse update ioctl. These ioctls must be generated by a mouse-aware user-mode application such as the gpm(8) daemon. Jared Finder has also confirmed in https://lore.kernel.org/all/491f3df9de6593df8e70dbe77614b026@finder.org/ that Emacs does not call TIOCL_SELMOUSEREPORT directly, and it would be difficult to find good reasons for doing that, given that it would interfere with the reports that GPM is sending. More information on the interaction between GPM, terminals and th ---truncated---
References
Impacted products
Vendor Product Version
Linux Linux Version: e46d91ca504d69ae3d09c120b162a238b8013890
Version: 2f83e38a095f8bf7c6029883d894668b03b9bd93
Version: 2f83e38a095f8bf7c6029883d894668b03b9bd93
Version: 2714ffdbb79b48dda03334a01af90fb024f39047
Version: 6.12.14   ≤
Version: 6.13.3   ≤
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/tty/vt/selection.c"
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          "versions": [
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              "versionType": "git"
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            {
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              "version": "2714ffdbb79b48dda03334a01af90fb024f39047",
              "versionType": "git"
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            {
              "lessThan": "6.12.26",
              "status": "affected",
              "version": "6.12.14",
              "versionType": "semver"
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            {
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              "status": "affected",
              "version": "6.13.3",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/tty/vt/selection.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.14"
            },
            {
              "lessThan": "6.14",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.26",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.14.*",
              "status": "unaffected",
              "version": "6.14.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.15",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
            {
              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.26",
                  "versionStartIncluding": "6.12.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.14.5",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                },
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                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.13.3",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntty: Require CAP_SYS_ADMIN for all usages of TIOCL_SELMOUSEREPORT\n\nThis requirement was overeagerly loosened in commit 2f83e38a095f\n(\"tty: Permit some TIOCL_SETSEL modes without CAP_SYS_ADMIN\"), but as\nit turns out,\n\n  (1) the logic I implemented there was inconsistent (apologies!),\n\n  (2) TIOCL_SELMOUSEREPORT might actually be a small security risk\n      after all, and\n\n  (3) TIOCL_SELMOUSEREPORT is only meant to be used by the mouse\n      daemon (GPM or Consolation), which runs as CAP_SYS_ADMIN\n      already.\n\nIn more detail:\n\n1. The previous patch has inconsistent logic:\n\n   In commit 2f83e38a095f (\"tty: Permit some TIOCL_SETSEL modes\n   without CAP_SYS_ADMIN\"), we checked for sel_mode ==\n   TIOCL_SELMOUSEREPORT, but overlooked that the lower four bits of\n   this \"mode\" parameter were actually used as an additional way to\n   pass an argument.  So the patch did actually still require\n   CAP_SYS_ADMIN, if any of the mouse button bits are set, but did not\n   require it if none of the mouse buttons bits are set.\n\n   This logic is inconsistent and was not intentional.  We should have\n   the same policies for using TIOCL_SELMOUSEREPORT independent of the\n   value of the \"hidden\" mouse button argument.\n\n   I sent a separate documentation patch to the man page list with\n   more details on TIOCL_SELMOUSEREPORT:\n   https://lore.kernel.org/all/20250223091342.35523-2-gnoack3000@gmail.com/\n\n2. TIOCL_SELMOUSEREPORT is indeed a potential security risk which can\n   let an attacker simulate \"keyboard\" input to command line\n   applications on the same terminal, like TIOCSTI and some other\n   TIOCLINUX \"selection mode\" IOCTLs.\n\n   By enabling mouse reporting on a terminal and then injecting mouse\n   reports through TIOCL_SELMOUSEREPORT, an attacker can simulate\n   mouse movements on the same terminal, similar to the TIOCSTI\n   keystroke injection attacks that were previously possible with\n   TIOCSTI and other TIOCL_SETSEL selection modes.\n\n   Many programs (including libreadline/bash) are then prone to\n   misinterpret these mouse reports as normal keyboard input because\n   they do not expect input in the X11 mouse protocol form.  The\n   attacker does not have complete control over the escape sequence,\n   but they can at least control the values of two consecutive bytes\n   in the binary mouse reporting escape sequence.\n\n   I went into more detail on that in the discussion at\n   https://lore.kernel.org/all/20250221.0a947528d8f3@gnoack.org/\n\n   It is not equally trivial to simulate arbitrary keystrokes as it\n   was with TIOCSTI (commit 83efeeeb3d04 (\"tty: Allow TIOCSTI to be\n   disabled\")), but the general mechanism is there, and together with\n   the small number of existing legit use cases (see below), it would\n   be better to revert back to requiring CAP_SYS_ADMIN for\n   TIOCL_SELMOUSEREPORT, as it was already the case before\n   commit 2f83e38a095f (\"tty: Permit some TIOCL_SETSEL modes without\n   CAP_SYS_ADMIN\").\n\n3. TIOCL_SELMOUSEREPORT is only used by the mouse daemons (GPM or\n   Consolation), and they are the only legit use case:\n\n   To quote console_codes(4):\n\n     The mouse tracking facility is intended to return\n     xterm(1)-compatible mouse status reports.  Because the console\n     driver has no way to know the device or type of the mouse, these\n     reports are returned in the console input stream only when the\n     virtual terminal driver receives a mouse update ioctl.  These\n     ioctls must be generated by a mouse-aware user-mode application\n     such as the gpm(8) daemon.\n\n   Jared Finder has also confirmed in\n   https://lore.kernel.org/all/491f3df9de6593df8e70dbe77614b026@finder.org/\n   that Emacs does not call TIOCL_SELMOUSEREPORT directly, and it\n   would be difficult to find good reasons for doing that, given that\n   it would interfere with the reports that GPM is sending.\n\n   More information on the interaction between GPM, terminals and th\n---truncated---"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - Exploitation requires a local `ioctl(TIOCLINUX, TIOCL_SETSEL)` on a Linux virtual console device (/dev/ttyN) that is the attacker\u0027s controlling terminal. There is no remote or network-facing path to `tioclinux()`.\nAC:L - The attacker controls every precondition: it enables mouse reporting itself by writing `\\033[?1000h` to the shared VT, then issues the ioctl deterministically with no race, no memory-layout dependency, and on the default CONFIG_VT=y configuration shipped by all distributions.\nPR:L - Only an ordinary unprivileged local account is needed \u2014 the sole gate is `current-\u003esignal-\u003etty == tty`, which any process running on the console satisfies, and the removed `CAP_SYS_ADMIN` check was precisely the bug.\nUI:N - The injected bytes are pushed into the tty flip buffer and are consumed automatically by whatever privileged process next reads the terminal; no victim action is required for the injection itself to land.\nS:U - Both the attacking process and the impacted privileged terminal session are managed by the same security authority \u2014 the kernel \u2014 so this is standard same-scope local privilege escalation.\nC:H - Successful input injection into a root shell lets the attacker drive commands whose output goes to the shared tty that the attacker still holds open and can read, yielding disclosure of arbitrary root-readable data.\nI:H - The flaw is a keystroke-injection primitive into a higher-privileged session \u2014 the maintainer states \"the general mechanism is there\" \u2014 and repeated calls accumulate attacker-chosen bytes in the privileged shell\u0027s line buffer, giving root-level command execution and arbitrary modification of system state.\nA:H - The attacker can flood the privileged terminal\u0027s input queue to wedge and corrupt that session, and the resulting root-level command injection permits fully destructive actions such as shutdown or data deletion."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T11:57:43.544Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/6f021bc0083b96125fdbed6a60d7b4396c4d6dac"
        },
        {
          "url": "https://git.kernel.org/stable/c/9b50c9c97db953de756a39af83d4be4d7f618aa6"
        },
        {
          "url": "https://git.kernel.org/stable/c/ee6a44da3c87cf64d67dd02be8c0127a5bf56175"
        }
      ],
      "title": "tty: Require CAP_SYS_ADMIN for all usages of TIOCL_SELMOUSEREPORT",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-37814",
    "datePublished": "2025-05-08T06:26:10.723Z",
    "dateReserved": "2025-04-16T04:51:23.946Z",
    "dateUpdated": "2026-08-05T11:57:43.544Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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