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OpenwrtOperating system

CVE-2026-62948

CRITICAL · 9.6 CVSS v3.1 Published 2026-07-15
Fix available
A fix is available. Upgrade to 25.12.5 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges 5 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
OpenWrt is a Linux operating system targeting embedded devices. Prior to 25.12.5, odhcpd writes a DHCPv6 client FQDN option 39 hostname into /tmp/odhcpd.leases through src/statefiles.c statefiles_write_state6() and statefiles_write_state4() without escaping, allowing newline injection of forged lease lines that LuCI rpcd-mod-luci getDHCPLeases displays through htdocs/luci-static/resources/view/status/include/40_dhcp.js and htdocs/luci-static/resources/luci.js dom.append as live HTML in the Active DHCPv6 Leases admin page. This vulnerability is fixed in 25.12.5.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

In odhcpd (OpenWrt DHCP daemon), DHCPv6 client FQDN option 39 hostnames are written to /tmp/odhcpd.leases without input sanitization. This allows newline injection to forge malicious lease entries. When LuCI's getDHCPLeases displays these leases in the Active DHCPv6 Leases admin page, the injected data is rendered as live HTML/JavaScript, enabling stored XSS against administrators.

MitigationUpdate OpenWrt to version 25.12.5 or later which implements proper hostname escaping in odhcpd's statefile writing functions, preventing newline injection and XSS.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
OpenwrtOperating system
Affected:< 25.12.5

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check OpenWrt version
    Run 'cat /etc/openwrt_version' or 'cat /etc/os-release' to identify the installed OpenWrt version
    Affected if The version is below 25.12.5 (e.g., 25.10.x, 24.x.x, or earlier)
  2. Verify odhcpd is active
    Check if odhcpd service is running using 'ps | grep odhcpd' or 'ubus call service list' to confirm odhcpd is actively handling DHCPv6 leases
    Affected if odhcpd is running and serving DHCPv6 clients with FQDN hostnames
  3. Confirm LuCI is installed
    Check if LuCI web interface is present by looking for 'luci' in installed packages via 'opkg list-installed | grep luci' or by accessing the web UI
    Affected if LuCI is installed and provides the getDHCPLeases API on the Active DHCPv6 Leases page
  4. Inspect lease file for unescaped content
    Examine /tmp/odhcpd.leases using 'cat /tmp/odhcpd.leases' to look for lease entries with unexpected newlines or unusual hostname patterns that may indicate injection
    Affected if The lease file contains entries with embedded newline characters or suspicious hostname data that was not properly escaped

You are affected if running OpenWrt version below 25.12.5 with odhcpd actively serving DHCPv6 clients that have FQDN hostnames, and LuCI is accessible to render those leases as HTML.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 25.12.5 or later
Fixed in 25.12.5
Interim mitigation

Update OpenWrt to version 25.12.5 or later which implements proper hostname escaping in odhcpd's statefile writing functions, preventing newline injection and XSS.

Recommended fix High confidence

OpenWrt 25.12.5

  1. 1. Backup the current OpenWrt configuration using `sysupgrade -b /tmp/backup.tar.gz` or LuCI system backup feature
  2. 2. Download the OpenWrt 25.12.5 firmware image from the official OpenWrt downloads (https://downloads.openwrt.org/) matching your device architecture
  3. 3. Verify the downloaded image checksum against the published SHA256 sums on the OpenWrt website
  4. 4. Upload the firmware image through LuCI (System > Backup/Flash Firmware > Flash new firmware image) or via SSH using `sysupgrade -v /path/to/openwrt-25.12.5.bin`
  5. 5. Wait for the device to reboot and apply the previous configuration backup if needed
  6. 6. Verify the upgrade was successful by checking System > Software for version 25.12.5 or running `cat /etc/openwrt_version`
  7. 7. Confirm the odhcpd package is updated by checking `opkg list-installed odhcpd`
Caveat Review OpenWrt 25.12 release notes for any configuration syntax changes or deprecated features before upgrading, as minor releases may include breaking changes to LuCI or network configuration

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Openwrt Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-62948 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data