CVE-2025-68259 (GCVE-0-2025-68259)
Vulnerability from cvelistv5
Published
2025-12-16 14:45
Modified
2025-12-16 14:45
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: Don't skip unrelated instruction if INT3/INTO is replaced When re-injecting a soft interrupt from an INT3, INT0, or (select) INTn instruction, discard the exception and retry the instruction if the code stream is changed (e.g. by a different vCPU) between when the CPU executes the instruction and when KVM decodes the instruction to get the next RIP. As effectively predicted by commit 6ef88d6e36c2 ("KVM: SVM: Re-inject INT3/INTO instead of retrying the instruction"), failure to verify that the correct INTn instruction was decoded can effectively clobber guest state due to decoding the wrong instruction and thus specifying the wrong next RIP. The bug most often manifests as "Oops: int3" panics on static branch checks in Linux guests. Enabling or disabling a static branch in Linux uses the kernel's "text poke" code patching mechanism. To modify code while other CPUs may be executing that code, Linux (temporarily) replaces the first byte of the original instruction with an int3 (opcode 0xcc), then patches in the new code stream except for the first byte, and finally replaces the int3 with the first byte of the new code stream. If a CPU hits the int3, i.e. executes the code while it's being modified, then the guest kernel must look up the RIP to determine how to handle the #BP, e.g. by emulating the new instruction. If the RIP is incorrect, then this lookup fails and the guest kernel panics. The bug reproduces almost instantly by hacking the guest kernel to repeatedly check a static branch[1] while running a drgn script[2] on the host to constantly swap out the memory containing the guest's TSS. [1]: https://gist.github.com/osandov/44d17c51c28c0ac998ea0334edf90b5a [2]: https://gist.github.com/osandov/10e45e45afa29b11e0c7209247afc00b
References
Impacted products
Vendor Product Version
Linux Linux Version: 6ef88d6e36c2b4b3886ec9967cafabe4424d27d5
Version: 6ef88d6e36c2b4b3886ec9967cafabe4424d27d5
Version: 6ef88d6e36c2b4b3886ec9967cafabe4424d27d5
Version: 6ef88d6e36c2b4b3886ec9967cafabe4424d27d5
 Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/x86/include/asm/kvm_host.h",
            "arch/x86/kvm/svm/svm.c",
            "arch/x86/kvm/x86.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "87cc1622c88a4888959d64fa1fc9ba1e264aa3d4",
              "status": "affected",
              "version": "6ef88d6e36c2b4b3886ec9967cafabe4424d27d5",
              "versionType": "git"
            },
            {
              "lessThan": "54bcccc2c7805a00af1d7d2faffd6f424c0133aa",
              "status": "affected",
              "version": "6ef88d6e36c2b4b3886ec9967cafabe4424d27d5",
              "versionType": "git"
            },
            {
              "lessThan": "53903ac9ca1abffa27327e85075ec496fa55ccf3",
              "status": "affected",
              "version": "6ef88d6e36c2b4b3886ec9967cafabe4424d27d5",
              "versionType": "git"
            },
            {
              "lessThan": "4da3768e1820cf15cced390242d8789aed34f54d",
              "status": "affected",
              "version": "6ef88d6e36c2b4b3886ec9967cafabe4424d27d5",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/x86/include/asm/kvm_host.h",
            "arch/x86/kvm/svm/svm.c",
            "arch/x86/kvm/x86.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.0"
            },
            {
              "lessThan": "6.0",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.62",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.17.*",
              "status": "unaffected",
              "version": "6.17.12",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.1",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.19-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.62",
                  "versionStartIncluding": "6.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.17.12",
                  "versionStartIncluding": "6.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.1",
                  "versionStartIncluding": "6.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19-rc1",
                  "versionStartIncluding": "6.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SVM: Don\u0027t skip unrelated instruction if INT3/INTO is replaced\n\nWhen re-injecting a soft interrupt from an INT3, INT0, or (select) INTn\ninstruction, discard the exception and retry the instruction if the code\nstream is changed (e.g. by a different vCPU) between when the CPU\nexecutes the instruction and when KVM decodes the instruction to get the\nnext RIP.\n\nAs effectively predicted by commit 6ef88d6e36c2 (\"KVM: SVM: Re-inject\nINT3/INTO instead of retrying the instruction\"), failure to verify that\nthe correct INTn instruction was decoded can effectively clobber guest\nstate due to decoding the wrong instruction and thus specifying the\nwrong next RIP.\n\nThe bug most often manifests as \"Oops: int3\" panics on static branch\nchecks in Linux guests.  Enabling or disabling a static branch in Linux\nuses the kernel\u0027s \"text poke\" code patching mechanism.  To modify code\nwhile other CPUs may be executing that code, Linux (temporarily)\nreplaces the first byte of the original instruction with an int3 (opcode\n0xcc), then patches in the new code stream except for the first byte,\nand finally replaces the int3 with the first byte of the new code\nstream.  If a CPU hits the int3, i.e. executes the code while it\u0027s being\nmodified, then the guest kernel must look up the RIP to determine how to\nhandle the #BP, e.g. by emulating the new instruction.  If the RIP is\nincorrect, then this lookup fails and the guest kernel panics.\n\nThe bug reproduces almost instantly by hacking the guest kernel to\nrepeatedly check a static branch[1] while running a drgn script[2] on\nthe host to constantly swap out the memory containing the guest\u0027s TSS.\n\n[1]: https://gist.github.com/osandov/44d17c51c28c0ac998ea0334edf90b5a\n[2]: https://gist.github.com/osandov/10e45e45afa29b11e0c7209247afc00b"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-12-16T14:45:01.753Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/87cc1622c88a4888959d64fa1fc9ba1e264aa3d4"
        },
        {
          "url": "https://git.kernel.org/stable/c/54bcccc2c7805a00af1d7d2faffd6f424c0133aa"
        },
        {
          "url": "https://git.kernel.org/stable/c/53903ac9ca1abffa27327e85075ec496fa55ccf3"
        },
        {
          "url": "https://git.kernel.org/stable/c/4da3768e1820cf15cced390242d8789aed34f54d"
        }
      ],
      "title": "KVM: SVM: Don\u0027t skip unrelated instruction if INT3/INTO is replaced",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-68259",
    "datePublished": "2025-12-16T14:45:01.753Z",
    "dateReserved": "2025-12-16T13:41:40.267Z",
    "dateUpdated": "2025-12-16T14:45:01.753Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-68259\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-12-16T15:15:55.320\",\"lastModified\":\"2025-12-18T15:08:06.237\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nKVM: SVM: Don\u0027t skip unrelated instruction if INT3/INTO is replaced\\n\\nWhen re-injecting a soft interrupt from an INT3, INT0, or (select) INTn\\ninstruction, discard the exception and retry the instruction if the code\\nstream is changed (e.g. by a different vCPU) between when the CPU\\nexecutes the instruction and when KVM decodes the instruction to get the\\nnext RIP.\\n\\nAs effectively predicted by commit 6ef88d6e36c2 (\\\"KVM: SVM: Re-inject\\nINT3/INTO instead of retrying the instruction\\\"), failure to verify that\\nthe correct INTn instruction was decoded can effectively clobber guest\\nstate due to decoding the wrong instruction and thus specifying the\\nwrong next RIP.\\n\\nThe bug most often manifests as \\\"Oops: int3\\\" panics on static branch\\nchecks in Linux guests.  Enabling or disabling a static branch in Linux\\nuses the kernel\u0027s \\\"text poke\\\" code patching mechanism.  To modify code\\nwhile other CPUs may be executing that code, Linux (temporarily)\\nreplaces the first byte of the original instruction with an int3 (opcode\\n0xcc), then patches in the new code stream except for the first byte,\\nand finally replaces the int3 with the first byte of the new code\\nstream.  If a CPU hits the int3, i.e. executes the code while it\u0027s being\\nmodified, then the guest kernel must look up the RIP to determine how to\\nhandle the #BP, e.g. by emulating the new instruction.  If the RIP is\\nincorrect, then this lookup fails and the guest kernel panics.\\n\\nThe bug reproduces almost instantly by hacking the guest kernel to\\nrepeatedly check a static branch[1] while running a drgn script[2] on\\nthe host to constantly swap out the memory containing the guest\u0027s TSS.\\n\\n[1]: https://gist.github.com/osandov/44d17c51c28c0ac998ea0334edf90b5a\\n[2]: https://gist.github.com/osandov/10e45e45afa29b11e0c7209247afc00b\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/4da3768e1820cf15cced390242d8789aed34f54d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/53903ac9ca1abffa27327e85075ec496fa55ccf3\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/54bcccc2c7805a00af1d7d2faffd6f424c0133aa\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/87cc1622c88a4888959d64fa1fc9ba1e264aa3d4\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.