CVE
Busybox: stack buffer overflow in udhcpc6 send_d6_renew() and send_d6_release()
Affects Red Hat Enterprise Linux 6 and Red Hat Hardened Images where BusyBox's udhcpc6 utility is explicitly invoked for IPv6 network configuration. No vendor rating or fixed version is listed.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- See vendor advisory
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. BusyBox's udhcpc6 utility is explicitly invoked for IPv6 network configuration
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 28/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
A stack buffer overflow in the udhcpc6 DHCPv6 client in BusyBox, as shipped in Red Hat Enterprise Linux 6 and Red Hat Hardened Images, lets a malicious DHCPv6 server on the same local network send a crafted reply that can run arbitrary code with root privileges or crash the client. The attacker must be on the adjacent local network, but needs no login or user action.
Read the original description
A flaw was found in BusyBox. The udhcpc6 DHCPv6 client does not properly validate the size of network options sent by a server before copying them into memory. A malicious DHCPv6 server on the local network can exploit this flaw by sending a crafted reply, triggering a stack-based buffer overflow. This vulnerability could allow an attacker to achieve arbitrary code execution with root privileges or cause a denial of service (DoS) crash.
Who should check
Teams running BusyBox udhcpc6 for IPv6 configuration on Red Hat Enterprise Linux 6 or Red Hat Hardened Images, in specialized or embedded environments
Read the source excerpt
“where BusyBox's udhcpc6 utility is explicitly invoked for IPv6 network configuration”
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure5/25Specific setups only
- Reach10/20Shipped in major Linux distributions
- Severity7.6/10CVSS 7.6
- No patch5/5No fixed version listed; see vendor advisory
What would change the score
- Would score about 78 if added to CISA KEV
- Would score about 73 if CISA's SSVC rates exploitation active
- Would score about 38 if CISA's SSVC rates it automatable
What to do
Check whether your setup matches what the bug needs.
BusyBox's udhcpc6 utility is explicitly invoked for IPv6 network configurationWorkaround: The checked facts list no fix and no workaround. Limiting exposure means avoiding explicit use of udhcpc6 for IPv6 network configuration while no fix is available.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-124741 (Busybox: stack buffer overflow in udhcpc6 send_d6_renew() and send_d6_release()), using the cve.now data below.
Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.
What cve.now has for CVE-2026-124741 (entry last updated 2026-11-11):
Affected:
- Red Hat Red Hat Enterprise Linux 6: version range not reported
- Red Hat Red Hat Hardened Images: version range not reported
Fixed versions: none listed yet.
Conditions (all must be true for the bug to be hit):
- BusyBox's udhcpc6 utility is explicitly invoked for IPv6 network configuration (source: https://access.redhat.com/security/cve/cve-2026-124741)
Setup: the bug needs a feature or setting that is off by default or uncommon. Check whether each asset has it on.
Attacker needs: adjacent access, no login, no user action.
CISA KEV: CVE-2026-124741 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-124741 only. If you also check another CVE, look up its own KEV status; never assume it from this one.
How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.
Verify against the linked advisories before concluding, and cite the date you read each one:
- https://bugzilla.redhat.com/show_bug.cgi?id=2571617
- https://access.redhat.com/security/cve/CVE-2026-124741
- https://access.redhat.com/security/cve/cve-2026-124741
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.
Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.
Entry: https://cve.now/CVE-2026-124741
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-124741"}.Timeline
- CVE published
- First seen by cve.now
Affected versions
- busybox
Version range not reported
- busybox
Version range not reported
Evidence 4
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Write-ups · 1
Establishes: Technical detail and context.
- Report
Other links · 1
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-124741
Is CVE-2026-124741 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
The bug is a stack buffer overflow in the send_d6_renew() and send_d6_release() functions of BusyBox's udhcpc6 DHCPv6 client. The reported impact is arbitrary code execution with root privileges or a denial of service crash of the udhcpc6 client.Source: access.redhat.com
Am I affected, and how do I check?
The listed products are Red Hat Enterprise Linux 6 and Red Hat Hardened Images, and the issue applies where udhcpc6 is explicitly invoked for IPv6 network configuration. The facts give no version ranges, so check whether the system uses udhcpc6 for IPv6 configuration and which BusyBox build it ships.Source: access.redhat.com
How do I fix CVE-2026-124741?
No fixed version is given in the checked facts, so check the Red Hat advisory for a fixed package and update to it once it is published. Until then, follow the no-patch guidance below.Source: access.redhat.com
What if there's no patch?
The checked facts list no fix and no workaround. Limiting exposure means avoiding explicit use of udhcpc6 for IPv6 network configuration while no fix is available.Source: access.redhat.com