CVE-2026-104086
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.
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
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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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
| Package | Affected | Fixed |
|---|---|---|
7zipDebian: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 less22.01+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 |
7zipDebian: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 less25.01+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 |
7zipDebian: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 less25.01+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 |
p7zipDebian: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 |
p7zipDebian:13 |
before 16.02+transitional.1 | 16.02+transitional.1 |
p7zipUbuntu: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 |
p7zipUbuntu:16.04:LTS |
All versions, plus listed versions 9.20.1~dfsg.1-4.29.20.1~dfsg.1-4.2ubuntu0.1 |
None known |
p7zipUbuntu:18.04:LTS |
All versions, plus listed versions 16.02+dfsg-416.02+dfsg-516.02+dfsg-6 |
None known |
p7zipUbuntu:20.04:LTS |
All versions, plus listed versions 16.02+dfsg-716.02+dfsg-7build1 |
None known |
p7zipUbuntu:22.04:LTS |
All versions, plus listed versions 16.02+dfsg-8 |
None known |
Show 5 moreShow less
| Package | Affected | Fixed |
|---|---|---|
7zipUbuntu: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 |
p7zipUbuntu:24.04:LTS |
All versions, plus listed versions 16.02+dfsg-816.02+transitional.1 |
None known |
7zipUbuntu: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 |
7zipUbuntu: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 |
7zipUbuntu: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
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE 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
sourceforge.net/p/sevenzip/discussion/45797/thread/db6922e1d0
7-zip.org
vulncheck.com/advisories/7-zip-squashfs-uninitialized-memory-disclosure-via-uid-gid-table
nvd.nist.gov/vuln/detail/CVE-2026-104086
github.com/advisories/GHSA-xhq8-p89q-r47c
security-tracker.debian.org/tracker/CVE-2026-104086
ubuntu.com/security/CVE-2026-104086
cve.org/CVERecord?id=CVE-2026-104086
Left out here: 21 versions. The JSON record has them.