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Tenda AC18 unverified firmware install in upgrade handler

CVE-2026-129258EUVD-2026-125935

CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:P

9.4CriticalCNA
Exploited
No known exploitation
Fix
See vendor advisory
Who is exposed
Not reported
Published
Last modified
Reference
Last checked
17/100 · provisional
None on Exploit-DB, Metasploit or GitHub
On X
View the cve.now post

Summary

Tenda AC18 devices have a firmware upgrade flaw in the upgrade handler at /cgi-bin/upgrade, where manipulating the upgradeFile argument leads to insufficient verification of data authenticity. An attacker on the network can exploit it remotely, but only with high-level privileges and without any user action.

Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.

Original description

A vulnerability was identified in Tenda AC18 15.03.05.05_multi/15.03.05.19 Build 6318. Affected by this vulnerability is an unknown functionality of the file /cgi-bin/upgrade of the component Firmware Upgrade Handler. Such manipulation of the argument upgradeFile leads to insufficient verification of data authenticity. The attack may be launched remotely. The exploit is publicly available and might be used.

cve.now Index

17Pcve.now Index 17 of 100 · methodology v3 · provisional
  • Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
  • Exposure3/25Reachable over the network · Unknown: No advisory context yet
  • Reach?/20Unknown. No tracked technology or package matched
  • Severity9.4/10CVSS 9.4
  • No patch5/5No fixed version listed; see vendor advisory

What would change the score

  • Would score about 72 if added to CISA KEV
  • Would score about 67 if CISA's SSVC rates exploitation active
  • Would score about 36 if advisories confirm default setups are exposed

How the score works · Rankings

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-2026-129258 (Tenda AC18 Firmware Upgrade upgrade data authenticity), 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-2026-129258 (entry last updated 2026-11-14):
Affected:
- Tenda AC18: versions 15.03.05.05_multi, 15.03.05.19 Build 6318
Fixed versions: none listed yet.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
CISA KEV: CVE-2026-129258 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-129258 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://vuldb.com/vuln/437295
- https://vuldb.com/vuln/437295/cti
- https://vuldb.com/cve/CVE-2026-129258
- https://vuldb.com/submit/1043033
- https://www.tenda.com.cn/
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-2026-129258
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-2026-129258"}.

Timeline

  1. CVE published
  2. First seen by cve.now
  3. Posted on X by cve.now

Affected versions

  • Tenda AC18

    15.03.05.05_multi, 15.03.05.19 Build 6318

Evidence 8

Vendor advisory · 1

Establishes: Affected and fixed versions.

  1. Link

CVE record · 2

Establishes: The identifier and description.

  1. Record
  2. Record

Public exploit code · 1

Establishes: Public exploit code exists (Exploit-DB, Metasploit, Nuclei and GitHub).

  1. Exploit

Other links · 4

  1. Advisory
  2. Advisory
  3. Advisory
  4. Advisory

Corrections

None so far.

Something wrong on this page? Report an error. Every fix is listed here.

Questions about CVE-2026-129258

Is CVE-2026-129258 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

Which versions are affected by CVE-2026-129258?

AC18: versions 15.03.05.05_multi, 15.03.05.19 Build 6318.Source: cve.now feed data

Sources

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