{"id":"DEBIAN-CVE-2026-48095","details":"7-Zip is a file archiver with a high compression ratio. Versions 26.00 and prior contain a heap buffer overflow vulnerability caused by an under-allocation in the NTFS compressed stream buffer (GetCuSize shift UB), potentially allowing attackers to cause arbitrary code execution or application crashes. CInStream::GetCuSize() in the NTFS handler computes the compression-unit buffer size as (UInt32)1 \u003c\u003c (BlockSizeLog + CompressionUnit), and a crafted image with ClusterSizeLog \u003e= 28 and CompressionUnit == 4 drives the exponent to 32, which is undefined behavior and collapses on x86/x64 so _inBuf is allocated as 1 byte. ReadStream_FALSE then writes up to 256 MB of attacker-controlled data into that 1-byte buffer in 64 KB iterations, and because the CInStream object sits only 304 bytes after _inBuf, its vtable pointer is overwritten and the next dispatched call achieves a vtable hijack. On 32-bit builds the overflow is unconditionally reached; on 64-bit it requires the parallel 8 GB _outBuf allocation to succeed, otherwise failing closed to denial of service. The NTFS handler is enabled by default in stock 7z.dll and, via signature-based fallback matching \"NTFS    \" at offset 3, will open a crafted image regardless of file extension during extraction or testing. Version 26.01 fixes the issue.","modified":"2026-09-14T17:03:16.725961628Z","published":"2026-06-05T15:16:53.520Z","upstream":["CVE-2026-48095"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-48095"}],"affected":[{"package":{"name":"7zip","ecosystem":"Debian:12","purl":"pkg:deb/debian/7zip?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"22.01+really26.01+dfsg-0+deb12u1"}]}],"versions":["22.01+dfsg-10~exp1","22.01+dfsg-8","22.01+dfsg-8+deb12u1","22.01+dfsg-9","22.01+really25.01+dfsg-0+deb12u1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-48095.json"}},{"package":{"name":"7zip","ecosystem":"Debian:13","purl":"pkg:deb/debian/7zip?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["24.09+dfsg-8","25.00+dfsg-1","25.01+dfsg-1","25.01+dfsg-1~deb13u1","25.01+dfsg-1~deb13u1~bpo12+1","25.01+dfsg-1~deb13u2","25.01+dfsg-2","25.01+dfsg-3","25.01+dfsg-4","25.01+dfsg-5","26.00+dfsg-1","26.00+dfsg-2","26.00+dfsg-3","26.00+dfsg-4","26.00+dfsg-5","26.00+dfsg1-1","26.00+dfsg1-2","26.00+dfsg1-3","26.01+dfsg-1","26.01+dfsg-2","26.01+dfsg-3","26.02+dfsg-1","26.02+dfsg-2","26.02+dfsg-3","26.03+dfsg-1","26.03+dfsg-2","26.03+dfsg-3"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-48095.json"}},{"package":{"name":"7zip","ecosystem":"Debian:14","purl":"pkg:deb/debian/7zip?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"26.01+dfsg-1"}]}],"versions":["24.09+dfsg-8","25.00+dfsg-1","25.01+dfsg-1","25.01+dfsg-1~deb13u1","25.01+dfsg-1~deb13u1~bpo12+1","25.01+dfsg-1~deb13u2","25.01+dfsg-2","25.01+dfsg-3","25.01+dfsg-4","25.01+dfsg-5","26.00+dfsg-1","26.00+dfsg-2","26.00+dfsg-3","26.00+dfsg-4","26.00+dfsg-5","26.00+dfsg1-1","26.00+dfsg1-2","26.00+dfsg1-3"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-48095.json"}},{"package":{"name":"p7zip","ecosystem":"Debian:12","purl":"pkg:deb/debian/p7zip?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"16.02+really26.01+dfsg-0+deb12u1"}]}],"versions":["16.02+dfsg-8","16.02+really25.01+dfsg-0+deb12u1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-48095.json"}},{"package":{"name":"p7zip","ecosystem":"Debian:13","purl":"pkg:deb/debian/p7zip?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"16.02+transitional.1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-48095.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"}]}