GHSL-2026-120: 7-Zip SquashFS BlockToNode uninitialized heap read
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| mcmilk | 7-Zip | affected |
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No data.
| Vendor | Product | Versions | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Mcmilk | 7-zip |
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| Source | ID | Title |
|---|---|---|
Debian DLA |
DLA-4681-1 | p7zip security update |
No CVSS v4.0
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.179% probability within 30 days)
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
7-zip
7-zip 7-zip |
|
| CPEs | cpe:2.3:a:7-zip:7-zip:*:*:*:*:*:*:*:* | |
| Vendors & Products |
7-zip
7-zip 7-zip |
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Mcmilk
Mcmilk 7-zip |
|
| Vendors & Products |
Mcmilk
Mcmilk 7-zip |
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 7-Zip is a file archiver with a high compression ratio. Versions 9.18 through 26.00 contain an uninitialized heap read in the SquashFS archive handler caused by a sparsely populated index array. In the SquashFS handler, _blockToNode is allocated with capacity for every metadata block but populated only when an inode crosses a block boundary, so a crafted image with few inodes spanning many blocks leaves most slots holding raw heap contents (the underlying allocator does not zero-initialize POD storage). When OpenDir looks up an attacker-influenced blockIndex (derived from the RootInode superblock field), it reads two of these uninitialized slots and passes them as the left/right bounds of a binary search over _nodesPos, which dereferences the midpoint without bounds checking; if the resulting value happens to match the search key, the returned index is used to read a full node struct from _nodes whose fields feed further directory parsing, forming a chained OOB read primitive that is heap-layout-dependent and not reliably triggerable. The SquashFS handler is enabled by default in stock 7z.dll and the issue triggers during Open() with no interaction beyond opening the file; impact is denial of service from wild-pointer dereference and potential heap information disclosure, with no write primitive. Version 26.01 fixes the issue. | |
| Title | GHSL-2026-120: 7-Zip SquashFS BlockToNode uninitialized heap read | |
| Weaknesses | CWE-125 CWE-908 |
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| References |
| |
| Metrics |
cvssV3_1
|