CVE-2026-48104: 7-Zip is a file archiver with a high compression ratio

Routine

MEDIUM 4.2UPGRADE

CVE-2026-48104 is a medium-severity flaw (CVSS 4.2) affecting 7-zip. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 u

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	4.2 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.2% (top 93%)
CISA exploited list	No
Weakness	CWE-125, CWE-908
Published	2026-06-05
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: 7-zip

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-05 17:16 UTCPublished CVE record published
2026-06-17 10:54 UTCUpdated Record last modified

7-zip 7-zip UPGRADE

Affected: >= 9.18 and < 26.01

Fixed in: 26.01

Safe to downgrade to: a release before 9.18

1. Check installed version

apt-cache policy 7-zip || rpm -q 7-zip || 7-zip --version

2. UPGRADE to 26.01 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade 7-zip

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade 7-zip

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 9.18 (Debian / Ubuntu)

apt-cache madison 7-zip sudo apt install 7-zip=<VERSION_BEFORE_9.18> sudo apt-mark hold 7-zip

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list 7-zip sudo dnf downgrade 7-zip-<VERSION_BEFORE_9.18> sudo dnf versionlock add 7-zip

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-48104?

7-zip: upgrade to 26.01. Exact commands for each OS are on this page.

Is CVE-2026-48104 being exploited?

CVE-2026-48104 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-48104 affect?

CVE-2026-48104 affects 7-zip. Severity is medium (CVSS 4.2). 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 allo

How urgent is CVE-2026-48104?

Priority 22/100. Public exploit reference

Software pages

7-Zip vulnerabilities

Related CVEs

CVE-2026-58052 LOW 3.3 UPGRADE 7-Zip for Windows through 26.01 fails to preserve the Mark-of-the-Web when extracting a crafted RAR5 archive,
CVE-2026-48112 MEDIUM 6.5 UPGRADE 7-Zip is a file archiver with a high compression ratio
CVE-2026-48111 MEDIUM 4.3 UPGRADE 7-Zip is a file archiver with a high compression ratio
CVE-2026-48103 MEDIUM 4.3 UPGRADE 7-Zip is a file archiver with a high compression ratio
CVE-2026-48102 LOW 3.1 UPGRADE 7-Zip is a file archiver with a high compression ratio

References

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