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CVE-2026-104086

7-Zip < 26.03 SquashFS Uninitialized Memory Disclosure via UID/GID Table

6.8 MediumFix available

7-Zip before 26.03 contains an uninitialized memory disclosure vulnerability in the SquashFS v4 archive handler (SquashfsHandler.cpp) that allows attackers to leak heap memory by crafting a malicious archive where the superblock’s no_ids field is set so that the final metadata block’s expected size is miscomputed and bypasses the size validation check. By listing or extracting the crafted archive, attackers can cause the application to return uninitialized heap memory as the kpidUserId and kpidGroupId properties, exposing potentially sensitive process memory contents to the user.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
None
User interaction
Passive

What an attacker can affect

Confidentiality
High
Integrity
None
Availability
None

Exploit likelihood

0.19%Unchanged since Oct 15, 2026
90%50%10%1%

What each source reports

CVE List Score used 6.8

7-Zip < 26.03 SquashFS Uninitialized Memory Disclosure via UID/GID Table

7-Zip before 26.03 contains an uninitialized memory disclosure vulnerability in the SquashFS v4 archive handler (SquashfsHandler.cpp) that allows attackers to leak heap memory by crafting a malicious archive where the superblock’s no_ids field is set so that the final metadata block’s expected size is miscomputed and bypasses the size validation check. By listing or extracting the crafted archive, attackers can cause the application to return uninitialized heap memory as the kpidUserId and kpidGroupId properties, exposing potentially sensitive process memory contents to the user.

Record
CVE-2026-104086
CVSS 4.0
6.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Weakness
CWE-908
Updated
2026-11-02
EUVDEUVD-2026-101032 6.8

7-Zip before 26.03 contains an uninitialized memory disclosure vulnerability in the SquashFS v4 archive handler (SquashfsHandler.cpp) that allows attackers to leak heap memory by crafting a malicious archive where the superblock’s no_ids field is set so that the final metadata block’s expected size is miscomputed and bypasses the size validation check. By listing or extracting the crafted archive, attackers can cause the application to return uninitialized heap memory as the kpidUserId and kpidGroupId properties, exposing potentially sensitive process memory contents to the user.

Record
EUVD-2026-101032
CVSS 4.0
6.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-xhq8-p89q-r47c 6.8

7-Zip before 26.03 contains an uninitialized memory disclosure vulnerability in the SquashFS v4...

7-Zip before 26.03 contains an uninitialized memory disclosure vulnerability in the SquashFS v4 archive handler (SquashfsHandler.cpp) that allows attackers to leak heap memory by crafting a malicious archive where the superblock’s no_ids field is set so that the final metadata block’s expected size is miscomputed and bypasses the size validation check. By listing or extracting the crafted archive, attackers can cause the application to return uninitialized heap memory as the kpidUserId and kpidGroupId properties, exposing potentially sensitive process memory contents to the user.

Record
GHSA-xhq8-p89q-r47c
CVSS 4.0
6.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Weakness
CWE-908
Updated
2026-11-02
NVD 6.8

7-Zip before 26.03 contains an uninitialized memory disclosure vulnerability in the SquashFS v4 archive handler (SquashfsHandler.cpp) that allows attackers to leak heap memory by crafting a malicious archive where the superblock’s no_ids field is set so that the final metadata block’s expected size is miscomputed and bypasses the size validation check. By listing or extracting the crafted archive, attackers can cause the application to return uninitialized heap memory as the kpidUserId and kpidGroupId properties, exposing potentially sensitive process memory contents to the user.

Record
CVE-2026-104086
CVSS 4.0
6.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Weakness
CWE-908
Updated
2026-11-02
OSVDEBIAN-CVE-2026-104086 6.8

7-Zip before 26.03 contains an uninitialized memory disclosure vulnerability in the SquashFS v4 archive handler (SquashfsHandler.cpp) that allows attackers to leak heap memory by crafting a malicious archive where the superblock’s no_ids field is set so that the final metadata block’s expected size is miscomputed and bypasses the size validation check. By listing or extracting the crafted archive, attackers can cause the application to return uninitialized heap memory as the kpidUserId and kpidGroupId properties, exposing potentially sensitive process memory contents to the user.

Record
DEBIAN-CVE-2026-104086
CVSS 4.0
6.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Updated
2026-11-02
OSVUBUNTU-CVE-2026-104086 6.8

7-Zip before 26.03 contains an uninitialized memory disclosure vulnerability in the SquashFS v4 archive handler (SquashfsHandler.cpp) that allows attackers to leak heap memory by crafting a malicious archive where the superblock’s no_ids field is set so that the final metadata block’s expected size is miscomputed and bypasses the size validation check. By listing or extracting the crafted archive, attackers can cause the application to return uninitialized heap memory as the kpidUserId and kpidGroupId properties, exposing potentially sensitive process memory contents to the user.

Record
UBUNTU-CVE-2026-104086
CVSS 4.0
6.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
7zip
Debian:12
All versions, plus listed versions
22.01+dfsg-10~exp122.01+dfsg-822.01+dfsg-8+deb12u122.01+dfsg-922.01+really25.01+dfsg-0+deb12u1
Show 45 moreShow less
22.01+really26.01+dfsg-0+deb12u122.01+really26.02+dfsg-0+deb12u123.01+dfsg-123.01+dfsg-1023.01+dfsg-1123.01+dfsg-1223.01+dfsg-223.01+dfsg-323.01+dfsg-423.01+dfsg-4~exp123.01+dfsg-523.01+dfsg-623.01+dfsg-723.01+dfsg-823.01+dfsg-924.05+dfsg-124.05+dfsg-224.05+dfsg-324.06+dfsg-124.06+dfsg-224.06+dfsg-324.06+dfsg-424.07+dfsg-124.07+dfsg-224.08+dfsg-124.08+dfsg-1~bpo12+124.08+dfsg-224.09+dfsg-124.09+dfsg-224.09+dfsg-2~bpo12+124.09+dfsg-324.09+dfsg-424.09+dfsg-524.09+dfsg-624.09+dfsg-724.09+dfsg-7~bpo12+124.09+dfsg-824.09+dfsg-8~bpo12+125.00+dfsg-125.01+dfsg-125.01+dfsg-1~deb13u125.01+dfsg-1~deb13u1~bpo12+125.01+dfsg-1~deb13u225.01+dfsg-225.01+dfsg-3
None known
7zip
Debian:13
All versions, plus listed versions
24.09+dfsg-825.00+dfsg-125.01+dfsg-125.01+dfsg-1~deb13u125.01+dfsg-1~deb13u1~bpo12+1
Show 24 moreShow less
25.01+dfsg-1~deb13u225.01+dfsg-225.01+dfsg-325.01+dfsg-425.01+dfsg-526.00+dfsg-126.00+dfsg-226.00+dfsg-326.00+dfsg-426.00+dfsg-526.00+dfsg1-126.00+dfsg1-226.00+dfsg1-326.01+dfsg-126.01+dfsg-226.01+dfsg-326.02+dfsg-126.02+dfsg-226.02+dfsg-326.03+dfsg-126.03+dfsg-226.03+dfsg-326.04+dfsg-126.05+dfsg-1
None known
7zip
Debian:14
before 26.03+dfsg-1, plus listed versions
24.09+dfsg-825.00+dfsg-125.01+dfsg-125.01+dfsg-1~deb13u125.01+dfsg-1~deb13u1~bpo12+1
Show 19 moreShow less
25.01+dfsg-1~deb13u225.01+dfsg-225.01+dfsg-325.01+dfsg-425.01+dfsg-526.00+dfsg-126.00+dfsg-226.00+dfsg-326.00+dfsg-426.00+dfsg-526.00+dfsg1-126.00+dfsg1-226.00+dfsg1-326.01+dfsg-126.01+dfsg-226.01+dfsg-326.02+dfsg-126.02+dfsg-226.02+dfsg-3
26.03+dfsg-1
p7zip
Debian:12
All versions, plus listed versions
16.02+dfsg-816.02+really25.01+dfsg-0+deb12u116.02+really26.01+dfsg-0+deb12u116.02+really26.02+dfsg-0+deb12u116.02+transitional.1
None known
p7zip
Debian:13
before 16.02+transitional.1
16.02+transitional.1
p7zip
Ubuntu:14.04:LTS
All versions, plus listed versions
9.20.1~dfsg.1-49.20.1~dfsg.1-4+deb7u1build0.14.04.19.20.1~dfsg.1-4+deb7u2build0.14.04.19.20.1~dfsg.1-4+deb7u3build0.14.04.1
None known
p7zip
Ubuntu:16.04:LTS
All versions, plus listed versions
9.20.1~dfsg.1-4.29.20.1~dfsg.1-4.2ubuntu0.1
None known
p7zip
Ubuntu:18.04:LTS
All versions, plus listed versions
16.02+dfsg-416.02+dfsg-516.02+dfsg-6
None known
p7zip
Ubuntu:20.04:LTS
All versions, plus listed versions
16.02+dfsg-716.02+dfsg-7build1
None known
p7zip
Ubuntu:22.04:LTS
All versions, plus listed versions
16.02+dfsg-8
None known
Show 5 moreShow less
Affected packages
PackageAffectedFixed
7zip
Ubuntu:Pro:22.04:LTS
All versions, plus listed versions
21.03~beta+dfsg-621.04~beta+dfsg-121.06+dfsg-121.07+dfsg-121.07+dfsg-221.07+dfsg-321.07+dfsg-421.07+dfsg-4ubuntu0.1~esm1
None known
p7zip
Ubuntu:24.04:LTS
All versions, plus listed versions
16.02+dfsg-816.02+transitional.1
None known
7zip
Ubuntu:Pro:24.04:LTS
All versions, plus listed versions
23.01+dfsg-323.01+dfsg-723.01+dfsg-823.01+dfsg-1123.01+dfsg-11ubuntu0.1~esm1
None known
7zip
Ubuntu:26.10
All versions, plus listed versions
26.00+dfsg-126.01+dfsg-226.01+dfsg-326.02+dfsg-126.02+dfsg-2
None known
7zip
Ubuntu:26.04:LTS
All versions, plus listed versions
25.01+dfsg-225.01+dfsg-325.01+dfsg-425.01+dfsg-526.00+dfsg-1
None known

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-104086 is a medium vulnerability (CVSS 6.8) in 7-zip, published October 14, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.19%, the 8th percentile. Fixed in 7zip 26.03+dfsg-1.

References

This page doesn't list everything

Left out here: 21 versions. The JSON record has them.

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