CVE-2024-35875 (GCVE-0-2024-35875)

Vulnerability from cvelistv5 – Published: 2024-05-19 08:34 – Updated: 2026-08-05 11:30
VLAI
Title
x86/coco: Require seeding RNG with RDRAND on CoCo systems
Summary
In the Linux kernel, the following vulnerability has been resolved: x86/coco: Require seeding RNG with RDRAND on CoCo systems There are few uses of CoCo that don't rely on working cryptography and hence a working RNG. Unfortunately, the CoCo threat model means that the VM host cannot be trusted and may actively work against guests to extract secrets or manipulate computation. Since a malicious host can modify or observe nearly all inputs to guests, the only remaining source of entropy for CoCo guests is RDRAND. If RDRAND is broken -- due to CPU hardware fault -- the RNG as a whole is meant to gracefully continue on gathering entropy from other sources, but since there aren't other sources on CoCo, this is catastrophic. This is mostly a concern at boot time when initially seeding the RNG, as after that the consequences of a broken RDRAND are much more theoretical. So, try at boot to seed the RNG using 256 bits of RDRAND output. If this fails, panic(). This will also trigger if the system is booted without RDRAND, as RDRAND is essential for a safe CoCo boot. Add this deliberately to be "just a CoCo x86 driver feature" and not part of the RNG itself. Many device drivers and platforms have some desire to contribute something to the RNG, and add_device_randomness() is specifically meant for this purpose. Any driver can call it with seed data of any quality, or even garbage quality, and it can only possibly make the quality of the RNG better or have no effect, but can never make it worse. Rather than trying to build something into the core of the RNG, consider the particular CoCo issue just a CoCo issue, and therefore separate it all out into driver (well, arch/platform) code. [ bp: Massage commit message. ]
Severity
8.4 (High)
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator (v2.0.3)
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: d8aa7eea78a1401cce39b3bb61ead0150044a3df , < 22943e4fe4b3a2dcbadc3d38d5bf840bbdbfe374 (git)
Affected: d8aa7eea78a1401cce39b3bb61ead0150044a3df , < 453b5f2dec276c1bb4ea078bf8c0da57ee4627e5 (git)
Affected: d8aa7eea78a1401cce39b3bb61ead0150044a3df , < 08044b08b37528b82f70a87576c692b4e4b7716e (git)
Affected: d8aa7eea78a1401cce39b3bb61ead0150044a3df , < 99485c4c026f024e7cb82da84c7951dbe3deb584 (git)
Create a notification for this product.
Linux Linux Affected: 4.15
Unaffected: 0 , < 4.15 (semver)
Unaffected: 6.1.85 , ≤ 6.1.* (semver)
Unaffected: 6.6.26 , ≤ 6.6.* (semver)
Unaffected: 6.8.5 , ≤ 6.8.* (semver)
Unaffected: 6.9 , ≤ * (original_commit_for_fix)
Create a notification for this product.
Show details on NVD website
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En lugar de intentar construir algo en el n\u00facleo del RNG, considere el problema particular de CoCo solo como un problema de CoCo y, por lo tanto, sep\u00e1relo todo en c\u00f3digo de controlador (bueno, 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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-04T18:58:31+00:00",
      "cve": "CVE-2024-35875",
      "id": "CVE-2024-35875",
      "initial_release_date": "2024-05-19T00:00:00+00:00",
      "product_status:fixed": "513",
      "product_status:known_affected": "70",
      "product_status:known_not_affected": "43",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: x86/coco: Require seeding RNG with RDRAND on CoCo systems",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2024/cve-2024-35875.json",
      "version": "3"
    },
    "vulnrichment": {
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This is read/write access to the vulnerable component\u0027s platform, i.e. local.\\nAC:L - The attacker directly creates the vulnerable condition \\u2014 the host supplies guest CPUID and can simply not advertise X86_FEATURE_RDRAND, after which arch_get_random_longs() returns 0 and every remaining entropy input (cmdline, TSC, bootloader seed, interrupt/device timings) is host-supplied or host-observable. No unpredictable precondition is required; the same state also arises unaided when x86_init_rdrand() disables faulty RDRAND.\\nPR:N - Privileges are measured against the vulnerable component \\u2014 the CoCo guest kernel \\u2014 and the host holds no account, credential, or privilege inside the guest at all. The weak seeding happens unconditionally during guest boot with no guest-side authentication.\\nUI:N - The defective seeding occurs automatically in setup_arch() on every guest boot; no action by any guest user or administrator is needed.\\nS:U - The vulnerable component (guest kernel RNG seeding) and the impacted component (that same guest\u0027s kernel and userspace secrets) sit in the same security authority. No guest-to-host escape or IOMMU boundary is crossed.\\nC:H - With RDRAND absent the entire input pool consists of values the host chose or can observe, so the host can reconstruct the CRNG state and predict all get_random_bytes()/getrandom()/urandom output \\u2014 disk-encryption keys, TLS/SSH private keys, session keys and IVs generated in the guest. That is a complete, total loss of the confidentiality guarantee CoCo exists to provide.\\nI:H - Predictable nonces and keys let the attacker forge signatures, authentication tokens and MACs produced inside the guest, and predictable net_secret/ts_secret enable off-path TCP sequence and syncookie forgery for data injection. Predictable stack canaries (boot_init_stack_canary runs straight off the unseeded pool) and predictable randomization secrets additionally hand the attacker reliable control-flow-hijack primitives.\\nA:H - Knowledge of the boot stack canary and other kernel randomization secrets converts otherwise-unreliable memory-corruption bugs into dependable code execution and full guest takeover, and predictable TCP ISN/syncookie secrets permit off-path RST injection that tears down the guest\u0027s connections.\"}]}], \"affected\": [{\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"d8aa7eea78a1401cce39b3bb61ead0150044a3df\", \"lessThan\": \"22943e4fe4b3a2dcbadc3d38d5bf840bbdbfe374\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"d8aa7eea78a1401cce39b3bb61ead0150044a3df\", \"lessThan\": \"453b5f2dec276c1bb4ea078bf8c0da57ee4627e5\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"d8aa7eea78a1401cce39b3bb61ead0150044a3df\", \"lessThan\": \"08044b08b37528b82f70a87576c692b4e4b7716e\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"d8aa7eea78a1401cce39b3bb61ead0150044a3df\", \"lessThan\": \"99485c4c026f024e7cb82da84c7951dbe3deb584\", \"versionType\": \"git\"}], \"programFiles\": [\"arch/x86/coco/core.c\", \"arch/x86/include/asm/coco.h\", \"arch/x86/kernel/setup.c\"], \"defaultStatus\": \"unaffected\"}, {\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"4.15\"}, {\"status\": \"unaffected\", \"version\": \"0\", \"lessThan\": \"4.15\", \"versionType\": \"semver\"}, {\"status\": \"unaffected\", \"version\": \"6.1.85\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.1.*\"}, {\"status\": \"unaffected\", \"version\": \"6.6.26\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.6.*\"}, {\"status\": \"unaffected\", \"version\": \"6.8.5\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.8.*\"}, {\"status\": \"unaffected\", \"version\": \"6.9\", \"versionType\": \"original_commit_for_fix\", \"lessThanOrEqual\": \"*\"}], \"programFiles\": [\"arch/x86/coco/core.c\", \"arch/x86/include/asm/coco.h\", \"arch/x86/kernel/setup.c\"], \"defaultStatus\": \"affected\"}], \"references\": [{\"url\": \"https://git.kernel.org/stable/c/22943e4fe4b3a2dcbadc3d38d5bf840bbdbfe374\"}, {\"url\": \"https://git.kernel.org/stable/c/453b5f2dec276c1bb4ea078bf8c0da57ee4627e5\"}, {\"url\": \"https://git.kernel.org/stable/c/08044b08b37528b82f70a87576c692b4e4b7716e\"}, {\"url\": \"https://git.kernel.org/stable/c/99485c4c026f024e7cb82da84c7951dbe3deb584\"}], \"x_generator\": {\"engine\": \"bippy-1.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"In the Linux kernel, the following vulnerability has been resolved:\\n\\nx86/coco: Require seeding RNG with RDRAND on CoCo systems\\n\\nThere are few uses of CoCo that don\u0027t rely on working cryptography and\\nhence a working RNG. Unfortunately, the CoCo threat model means that the\\nVM host cannot be trusted and may actively work against guests to\\nextract secrets or manipulate computation. Since a malicious host can\\nmodify or observe nearly all inputs to guests, the only remaining source\\nof entropy for CoCo guests is RDRAND.\\n\\nIf RDRAND is broken -- due to CPU hardware fault -- the RNG as a whole\\nis meant to gracefully continue on gathering entropy from other sources,\\nbut since there aren\u0027t other sources on CoCo, this is catastrophic.\\nThis is mostly a concern at boot time when initially seeding the RNG, as\\nafter that the consequences of a broken RDRAND are much more\\ntheoretical.\\n\\nSo, try at boot to seed the RNG using 256 bits of RDRAND output. If this\\nfails, panic(). This will also trigger if the system is booted without\\nRDRAND, as RDRAND is essential for a safe CoCo boot.\\n\\nAdd this deliberately to be \\\"just a CoCo x86 driver feature\\\" and not\\npart of the RNG itself. Many device drivers and platforms have some\\ndesire to contribute something to the RNG, and add_device_randomness()\\nis specifically meant for this purpose.\\n\\nAny driver can call it with seed data of any quality, or even garbage\\nquality, and it can only possibly make the quality of the RNG better or\\nhave no effect, but can never make it worse.\\n\\nRather than trying to build something into the core of the RNG, consider\\nthe particular CoCo issue just a CoCo issue, and therefore separate it\\nall out into driver (well, arch/platform) code.\\n\\n  [ bp: Massage commit message. ]\"}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.1.85\", \"versionStartIncluding\": \"4.15\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.6.26\", \"versionStartIncluding\": \"4.15\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.8.5\", \"versionStartIncluding\": \"4.15\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.9\", \"versionStartIncluding\": \"4.15\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2026-08-05T11:30:35.909Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2024-35875\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-08-05T11:30:35.909Z\", \"dateReserved\": \"2024-05-17T13:50:33.110Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2024-05-19T08:34:32.767Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
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    }
  }
}



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Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.