UBUNTU-CVE-2026-72197: High severity ubuntu/linux-hwe-edge vulnerability
In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: bound DeleteIndexEntryAllocation memmove length In doaction()'s DeleteIndexEntryAllocation case, e->size comes from an on-disk INDEXBUFFER entry. When e->size makes e + e->size point past hdr + hdr->used, PtrOffset(e1, Add2Ptr(hdr, used)) returns a negative ptrdifft that is silently cast to a quasi-infinite sizet when passed to memmove(). The memmove then walks past the destination buffer. The sibling DeleteIndexEntryRoot case at fslog.c:3540-3543 already carries the corresponding guard: if (PtrOffset(e1, Add2Ptr(hdr, used)) < esize || Add2Ptr(e, esize) > Add2Ptr(lrh, reclen) || used + esize > le32tocpu(hdr->total)) { goto dirtyvol; } Apply the same shape to the allocation-path case. Also reject esize == 0: memmove(e, e, ...) is a no-op and leaves hdr->used unchanged, hiding a malformed entry from the existing checkindexheader() walk. Reproduced under UML+KASAN on mainline 8d90b09e6741 by mounting a crafted NTFS image: the unguarded memmove takes a length of 0xffffffffffffff00 and the kernel oopses in memmove+0x81/0x1a0 on the doaction+0x36a2 frame. [almaz.alexandrovich@paragon-software.com: clang-formatted the changes]
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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ubuntu/linux-aws-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1117.124~20.04.1 - Upgrade
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ubuntu/linux-gcp-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1118.128~20.04.1 - Upgrade
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ubuntu/linux-hwe-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-198.208~20.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 5.15.0-198.208 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 5.15.0-1117.124 - Upgrade
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ubuntu/linux-aws-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1067.70+fips1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-38.38 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 7.0.0-1016.16 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 7.0.0-1008.9 - Upgrade
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1013.13 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1
Event History
Frequently Asked Questions
Who is exposed to this issue?
Systems running one of the listed Ubuntu kernel packages are exposed when the NTFS3 filesystem code processes a malformed on-disk NTFS index buffer. The reproduced attack path involved mounting a crafted NTFS image.
What does an attacker need to exploit it?
An attacker needs to cause the system to mount or otherwise process a crafted NTFS filesystem image containing a malformed INDEX_BUFFER entry. The supplied vector indicates local access, no privileges, and no user interaction are required.
What can be done before a patched kernel is deployed?
Avoid mounting NTFS images from untrusted sources, particularly images that may contain crafted filesystem metadata. Restrict access to removable media or disk images where practical.
What evidence might indicate exploitation or exposure?
The reported reproduction caused the kernel to oops in memmove, with do_action on the call frame, after processing a crafted NTFS image. KASAN observed an excessively large memmove length during the reproduction.