CVE-2026-64074 (GCVE-0-2026-64074)

Vulnerability from cvelistv5 – Published: 2026-07-19 15:39 – Updated: 2026-08-05 12:38
VLAI
Title
fs/statmount: fix slab out-of-bounds write in statmount_mnt_idmap
Summary
In the Linux kernel, the following vulnerability has been resolved: fs/statmount: fix slab out-of-bounds write in statmount_mnt_idmap statmount_mnt_idmap() writes one mapping with seq_printf() and then manually advances seq->count to include the NUL separator. If seq_printf() overflows, seq_set_overflow() sets seq->count to seq->size. The manual seq->count++ changes this to seq->size + 1. seq_has_overflowed() then no longer detects the overflow. The corrupted count returns to statmount_string(), which later executes: seq->buf[seq->count++] = '\0'; This causes a 1-byte NULL out-of-bounds write on the dynamically allocated seq buffer. Fix this by checking for overflow immediately after seq_printf().
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 54/100 over 6618 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 37c4a9590e1efcae7749682239fc22a330d2d325 , < e37ea2c6f17f273813ea4e8e94c102591d598ce1 (git)
Affected: 37c4a9590e1efcae7749682239fc22a330d2d325 , < 93614949dc86f068e3c32c32cf1ee2a2323177a7 (git)
Affected: 37c4a9590e1efcae7749682239fc22a330d2d325 , < a3bf0f28d4ba16e1f35f8c983bb04426b87e2a78 (git)
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Linux Linux Affected: 6.15
Unaffected: 0 , < 6.15 (semver)
Unaffected: 6.18.34 , ≤ 6.18.* (semver)
Unaffected: 7.0.11 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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              "value": "AV:L - The bug is reachable only through the statmount(2) syscall when requesting mount UID/GID map strings; there is no network, adjacent, or physical entry path to this code.\nAC:L - An attacker fully controls statmount mask, buffer sizing, mount paths/options, and idmap extent values to reliably drive seq_printf() to overflow at the vulnerable count++ site without depending on uncontrollable timing or layout.\nPR:L - Exploitation requires creating or querying an idmapped mount via statmount, which an unprivileged local user can do in their own user/mount namespaces where CAP_SYS_ADMIN is granted by user namespaces.\nUI:N - Triggering the flaw requires only the attacker\u0027s own statmount syscall and crafted namespace/mount setup; no action by another user or victim is needed.\nS:U - Impact is kernel heap corruption and potential privilege escalation within the same kernel security domain, not a cross-boundary escape such as VM guest-to-host.\nC:H - The flaw is a slab out-of-bounds write that corrupts adjacent heap memory; per kernel CVSS guidance, exploitable memory corruption warrants High confidentiality impact even if direct read is not guaranteed.\nI:H - A one-byte out-of-bounds NULL write into adjacent kmalloc slab objects can corrupt kernel metadata and be leveraged for arbitrary memory modification or code execution.\nA:H - Heap corruption from the out-of-bounds write can cause kernel oops/panic or destabilize the system, and memory-corruption bugs are scored as High availability impact."
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}



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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.

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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.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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