CVE-2026-38755: A heap overflow in the evalcommand() function (shell/ash.c) of Busybox v1.38.0 allows attackers to cause a Den

Routine

LOW 2.9DOWNGRADE

CVE-2026-38755 is a low-severity flaw (CVSS 2.9) affecting busybox. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A heap overflow in the evalcommand() function (shell/ash.c) of Busybox v1.38.0 allows attackers to cause a Denial of Service (DoS) via supplying a crafted input.

Why this priority

No elevated risk signals yet

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	2.9 (Low)
Attack vector	Local
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 89%)
CISA exploited list	No
Weakness	CWE-674, CWE-122
Published	2026-07-15
Last modified	2026-07-20

Publisher (CNA): MITRE · Vendor: busybox

Last updated 2026-07-20 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-15 22:16 UTCPublished CVE record published
2026-07-20 16:16 UTCUpdated Record last modified

busybox busybox DOWNGRADE

Affected: 1.38.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.38.0

1. Check installed version

apt-cache policy busybox || rpm -q busybox || busybox --version

2. No fixed release: DOWNGRADE to a release before 1.38.0 (Debian / Ubuntu)

apt-cache madison busybox sudo apt install busybox=<VERSION_BEFORE_1.38.0> sudo apt-mark hold busybox

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list busybox sudo dnf downgrade busybox-<VERSION_BEFORE_1.38.0> sudo dnf versionlock add busybox

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-2026-38755?

busybox: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-38755 being exploited?

CVE-2026-38755 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-2026-38755 affect?

CVE-2026-38755 affects busybox. Severity is low (CVSS 2.9). A heap overflow in the evalcommand() function (shell/ash.c) of Busybox v1.38.0 allows attackers to cause a Denial of Service (DoS) via supplying a crafted input.

How urgent is CVE-2026-38755?

Priority 13/100. No elevated risk signals yet.

Related CVEs

CVE-2026-38754 MEDIUM 5.1 DOWNGRADE A heap overflow in the ifsbreakup() function (shell/ash.c) of Busybox v1.38.0 allows attackers to cause a Deni
CVE-2026-38753 MEDIUM 4.9 DOWNGRADE A use-after-free in the awk_sub() function (editors/awk.c) of Busybox v1.38.0 allows attackers to cause a Deni
CVE-2026-38752 LOW 2.9 DOWNGRADE A stack overflow in the evaluate() function (editors/awk.c) of BusyBox commit 371fe9 allows attackers to cause

References

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