CVE-2026-88831VulnerabilityPublished 25 Sep 2026Updated 22 Oct 2026

Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update

Affects Red Hat busyboxSource GCVE Database

Authoritative record:CVE-2026-88831· Medium 5.3

Not known to be exploited · CVSS 5.3 Medium · fixed in Red Hat package updates : update the Red Hat redhat/busybox package when convenient.

Data as of 7 Nov 2026, 23:24 UTC

CVSS 3.1 base score

5.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 14% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.37.0-9.1.hum1, 1.36.1-25.oe2403sp1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 23 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 9 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade the Red Hat redhat/busybox package to 1.37.0-9.1.hum1; busybox to 1.36.1-25.oe2403sp1.

Affected software

Product	Affected	Fixed in
Red Hatredhat/busybox`pkg:rpm/redhat/busybox`Other threats	Affected <1.37.0-9.1.hum1	Fixed in 1.37.0-9.1.hum1
Ubuntu Pro 14.04 LTSbusybox`pkg:deb/ubuntu/busybox?arch=source&distro=esm-infra-legacy/trusty`Other threats	Affected 1:1.20.0-8.1ubuntu1 – 1:1.21.0-1ubuntu1.4+esm1 6 affected builds	Fixed in–
Ubuntu Pro 16.04 LTSbusybox`pkg:deb/ubuntu/busybox?arch=source&distro=esm-infra/xenial`Other threats	Affected 1:1.22.0-15ubuntu1 – 1:1.22.0-15ubuntu1.4+esm2 4 affected builds	Fixed in–
Ubuntu Pro 18.04 LTSbusybox`pkg:deb/ubuntu/busybox?arch=source&distro=esm-infra/bionic`Other threats	Affected 1:1.22.0-19ubuntu2 – 1:1.27.2-2ubuntu3.4+esm1 10 affected builds	Fixed in–
Ubuntu 20.04 LTSbusybox`pkg:deb/ubuntu/busybox?arch=source&distro=focal`Other threats	Affected 1:1.30.1-4ubuntu4 – 1:1.30.1-4ubuntu6.5 8 affected builds	Fixed in–
Ubuntu 22.04 LTSbusybox`pkg:deb/ubuntu/busybox?arch=source&distro=jammy`Other threats	Affected 1:1.30.1-6ubuntu3 – 1:1.30.1-7ubuntu3.1 5 affected builds	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in BusyBox version 1.37.0-9.1.hum1 and later. Users should update to this version to remediate the vulnerabilities. Additionally, audit all BusyBox httpd configuration files to ensure CIDR prefix lengths are syntactically valid. Implement network-level access controls such as iptables or nftables as the primary enforcement mechanism rather than relying solely on application-level access control lists.

Description

This Red Hat security advisory addresses multiple vulnerabilities in BusyBox RPMs included in Red Hat Hardened Images. Notably, CVE-2026-88831 involves BusyBox httpd silently failing open when IP deny rules contain invalid CIDR prefix lengths, allowing unintended network clients to access protected content. The advisory provides updated BusyBox packages that fix these issues.

Impact

The primary impact is that BusyBox httpd may allow network clients that should be blocked to access protected content due to failure to enforce IP deny rules with invalid CIDR masks. This can lead to unauthorized access to resources protected by BusyBox httpd ACLs. However, BusyBox httpd is rarely used as a production web server on Fedora, and exploitation requires a misconfiguration in the CIDR mask. The overall severity is rated high by Red Hat.

Summary

The advisory covers security fixes for BusyBox packages in Red Hat Hardened Images, including CVE-2026-88831, which causes BusyBox httpd to ignore malformed IP deny rules due to invalid CIDR prefix lengths. This flaw results in the httpd server failing open, meaning clients that should be blocked may gain access. The issue requires misconfigured CIDR masks in the httpd configuration and is mitigated by auditing configuration files and using network-level access controls. The update includes BusyBox version 1.37.0-9.1.hum1, which contains the fixes.

CWE-636Not Failing Securely (Failing Open) (opens in a new tab)
Class weaknessOWASP Top 10 A10:2025: Mishandling of Exceptional Conditions (opens in a new tab)
When the product encounters an error condition or failure, its design requires it to fall back to a state that is less secure than other options that are available, such as selecting the weakest encryption algorithm or using the most permissive access control restrictions.
Architecture and Design
Subdivide and allocate resources and components so that a failure in one part does not affect the entire product.
OWASP Cheat Sheets
Logging (opens in a new tab)
Error Handling (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-787Out-of-bounds Write (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #5
The product writes data past the end, or before the beginning, of the intended buffer.
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Operation · Build and Compilation · Environment Hardening
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index…
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-125Out-of-bounds Read (opens in a new tab)
Base weaknessCWE Top 25 (2025): #8
The product reads data past the end, or before the beginning, of the intended buffer.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Architecture and Design · Language Selection
Use a language that provides appropriate memory abstractions.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Overread Buffers (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-305Authentication Bypass by Primary Weakness (opens in a new tab)
Base weaknessOWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
The authentication algorithm is sound, but the implemented mechanism can be bypassed as the result of a separate weakness that is primary to the authentication error.
OWASP Cheat Sheets
OWASP Authentication (opens in a new tab)
OWASP ASVS 4.0.3
V2.8.5 (opens in a new tab)
V2.8.4 (opens in a new tab)
V9.2.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 3 Nov 2026, 09:45 UTC

WeaknessesCWE-636, CWE-787, CWE-125 +1

Technical details

References

Community reviews

Related threats