CVE-2026-64026 (GCVE-0-2026-64026)

Vulnerability from cvelistv5 – Published: 2026-07-19 15:39 – Updated: 2026-07-20 13:42
VLAI
Title
rxrpc: Fix DATA decrypt vs splice() by copying data to buffer in recvmsg
Summary
In the Linux kernel, the following vulnerability has been resolved: rxrpc: Fix DATA decrypt vs splice() by copying data to buffer in recvmsg This improves the fix for CVE-2026-43500. Fix the pagecache corruption from in-place decryption of a DATA packet transmitted locally by splice() by getting rid of the packet sharing in the I/O thread and unconditionally extracting the packet content into a bounce buffer in which the buffer is decrypted. recvmsg() (or the kernel equivalent) then copies the data from the bounce buffer to the destination buffer. The sk_buff then remains unmodified. This has an additional advantage in that the packet is then arranged in the buffer with the correct alignment required for the crypto algorithms to process directly. The performance of the crypto does seem to be a little faster and, surprisingly, the unencrypted performance doesn't seem to change much - possibly due to removing complexity from the I/O thread. Yet another advantage is that the I/O thread doesn't have to copy packets which would slow down packet distribution, ACK generation, etc.. The buffer belongs to the call and is allocated initially at 2K, sufficiently large to hold a whole jumbo subpacket, but the buffer will be increased in size if needed. However, to take this work, MSG_PEEK may cause a later packet to be decrypted into the buffer, in which case the earlier one will need re-decrypting for a subsequent recvmsg(). Note that rx_pkt_offset may legitimately see 0 as a valid offset now, so switch to using USHRT_MAX to indicate an invalid offset. Note also that I would generally prefer to replace the buffers of the current sk_buff with a new kmalloc'd buffer of the right size, ditching the old data and frags as this makes the handling of MSG_PEEK easier and removes the re-decryption issue, but this looks like quite a complicated thing to achieve. skb_morph() looks half way to what I want, but I don't want to have to allocate a new sk_buff.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: d0d5c0cd1e711c98703f3544c1e6fc1372898de5 , < a05bf6d9e621fa71e89ccebe3047ba45218d7b38 (git)
Affected: d0d5c0cd1e711c98703f3544c1e6fc1372898de5 , < b94a6ccbaf1104dd980150a65fdeb2f69d17d2f5 (git)
Affected: d0d5c0cd1e711c98703f3544c1e6fc1372898de5 , < 46cb765e2e5ad52303ea157e10d370bb6b7acbbf (git)
Affected: d0d5c0cd1e711c98703f3544c1e6fc1372898de5 , < c580087743712112778a06d65a4074053072d7bf (git)
Affected: d0d5c0cd1e711c98703f3544c1e6fc1372898de5 , < d2bc90cf6c75cb96d2ce549be6c35efa3099d25b (git)
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Linux Linux Affected: 5.3
Unaffected: 0 , < 5.3 (semver)
Unaffected: 6.6.143 , ≤ 6.6.* (semver)
Unaffected: 6.12.93 , ≤ 6.12.* (semver)
Unaffected: 6.18.35 , ≤ 6.18.* (semver)
Unaffected: 7.0.11 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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{
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            "net/rxrpc/recvmsg.c",
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            "net/rxrpc/rxgk_common.h",
            "net/rxrpc/rxkad.c"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nrxrpc: Fix DATA decrypt vs splice() by copying data to buffer in recvmsg\n\nThis improves the fix for CVE-2026-43500.\n\nFix the pagecache corruption from in-place decryption of a DATA packet\ntransmitted locally by splice() by getting rid of the packet sharing in the\nI/O thread and unconditionally extracting the packet content into a bounce\nbuffer in which the buffer is decrypted.  recvmsg() (or the kernel\nequivalent) then copies the data from the bounce buffer to the destination\nbuffer.  The sk_buff then remains unmodified.\n\nThis has an additional advantage in that the packet is then arranged in the\nbuffer with the correct alignment required for the crypto algorithms to\nprocess directly.  The performance of the crypto does seem to be a little\nfaster and, surprisingly, the unencrypted performance doesn\u0027t seem to\nchange much - possibly due to removing complexity from the I/O thread.\n\nYet another advantage is that the I/O thread doesn\u0027t have to copy packets\nwhich would slow down packet distribution, ACK generation, etc..\n\nThe buffer belongs to the call and is allocated initially at 2K,\nsufficiently large to hold a whole jumbo subpacket, but the buffer will be\nincreased in size if needed.  However, to take this work, MSG_PEEK may\ncause a later packet to be decrypted into the buffer, in which case the\nearlier one will need re-decrypting for a subsequent recvmsg().\n\nNote that rx_pkt_offset may legitimately see 0 as a valid offset now, so\nswitch to using USHRT_MAX to indicate an invalid offset.\n\nNote also that I would generally prefer to replace the buffers of the\ncurrent sk_buff with a new kmalloc\u0027d buffer of the right size, ditching the\nold data and frags as this makes the handling of MSG_PEEK easier and\nremoves the re-decryption issue, but this looks like quite a complicated\nthing to achieve.  skb_morph() looks half way to what I want, but I don\u0027t\nwant to have to allocate a new sk_buff."
        }
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    "dateReserved": "2026-07-19T07:54:57.028Z",
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However, to take this work, MSG_PEEK may\\ncause a later packet to be decrypted into the buffer, in which case the\\nearlier one will need re-decrypting for a subsequent recvmsg().\\n\\nNote that rx_pkt_offset may legitimately see 0 as a valid offset now, so\\nswitch to using USHRT_MAX to indicate an invalid offset.\\n\\nNote also that I would generally prefer to replace the buffers of the\\ncurrent sk_buff with a new kmalloc\u0027d buffer of the right size, ditching the\\nold data and frags as this makes the handling of MSG_PEEK easier and\\nremoves the re-decryption issue, but this looks like quite a complicated\\nthing to achieve.  skb_morph() looks half way to what I want, but I don\u0027t\\nwant to have to allocate a new sk_buff.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"net/rxrpc/ar-internal.h\",\"net/rxrpc/call_event.c\",\"net/rxrpc/call_object.c\",\"net/rxrpc/insecure.c\",\"net/rxrpc/recvmsg.c\",\"net/rxrpc/rxgk.c\",\"net/rxrpc/rxgk_common.h\",\"net/rxrpc/rxkad.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"d0d5c0cd1e711c98703f3544c1e6fc1372898de5\",\"lessThan\":\"a05bf6d9e621fa71e89ccebe3047ba45218d7b38\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"d0d5c0cd1e711c98703f3544c1e6fc1372898de5\",\"lessThan\":\"b94a6ccbaf1104dd980150a65fdeb2f69d17d2f5\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"d0d5c0cd1e711c98703f3544c1e6fc1372898de5\",\"lessThan\":\"46cb765e2e5ad52303ea157e10d370bb6b7acbbf\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"d0d5c0cd1e711c98703f3544c1e6fc1372898de5\",\"lessThan\":\"c580087743712112778a06d65a4074053072d7bf\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"d0d5c0cd1e711c98703f3544c1e6fc1372898de5\",\"lessThan\":\"d2bc90cf6c75cb96d2ce549be6c35efa3099d25b\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"net/rxrpc/ar-internal.h\",\"net/rxrpc/call_event.c\",\"net/rxrpc/call_object.c\",\"net/rxrpc/insecure.c\",\"net/rxrpc/recvmsg.c\",\"net/rxrpc/rxgk.c\",\"net/rxrpc/rxgk_common.h\",\"net/rxrpc/rxkad.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5.3\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"5.3\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.143\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.93\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.35\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.0.11\",\"lessThanOrEqual\":\"7.0.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/46cb765e2e5ad52303ea157e10d370bb6b7acbbf\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/a05bf6d9e621fa71e89ccebe3047ba45218d7b38\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b94a6ccbaf1104dd980150a65fdeb2f69d17d2f5\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/c580087743712112778a06d65a4074053072d7bf\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/d2bc90cf6c75cb96d2ce549be6c35efa3099d25b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}



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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

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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.
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Detection rules are retrieved from Rulezet.