TOTOLINK A950RG Easy Setup Wizard cstecgi.cgi setAppEasyWizardConfig stack-based overflow
Only affects TOTOLINK A950RG firmware V4.1.2cu.5268_B20221104 when the Easy Setup Wizard uses the repeater branch with a long SSID value. No fix is listed in the checked facts.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- No fix listed
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. Affected firmware is TOTOLINK A950RG V4.1.2cu.5268_B20221104. The functionType value must select the repeater branch of the handler. The rootSsid or apcliSsid value must be 157 bytes or longer to overwrite the saved return address.
- Exploitation?/40Exploitation: unknown (data gap). No CISA SSVC exploitation rating yet
- Exposure8/25Specific setups only, reachable over the network
- Reach?/20Reach: unknown (data gap). No tracked technology or package matched
- Severity9.4/10CVSS 9.4
- No patch5/5No patch listed yet
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 29 if CISA's SSVC rates it automatable
CVE-2026-121597 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 9.4 (critical) and affects A950RG; no fixed version is listed yet.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- Published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- FIRST's estimate of the chance attackers exploit it in the next 30 days, updated daily.What do these mean? →
- 0.60% · 48th percentile
- 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? →
- 22/100 · 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
The TOTOLINK A950RG router's Easy Setup Wizard, reached through its web interface, is affected. A remote attacker who manipulates a specific input parameter could trigger a stack-based buffer overflow, potentially crashing the device or taking control of it.
Read the original description
A weakness has been identified in TOTOLINK A950RG 4.1.2cu.5268_B20221104. This affects the function setAppEasyWizardConfig of the file /cgi-bin/cstecgi.cgi of the component Easy Setup Wizard Handler. Executing a manipulation of the argument functionType can lead to stack-based buffer overflow. The attack may be performed from remote. The exploit has been made available to the public and could be used for attacks.
What to do
Check whether your setup matches what the bug needs.
Affected firmware is TOTOLINK A950RG V4.1.2cu.5268_B20221104. The functionType value must select the repeater branch of the handler. The rootSsid or apcliSsid value must be 157 bytes or longer to overwrite the saved return address.Workaround: The checked facts list no workaround. The overflow depends on the repeater branch and long SSID values, so avoiding the repeater setup path in the Easy Setup Wizard is the only limiting step the facts suggest, and it is not confirmed by the vendor.
Timeline
- CVE published
- First seen by cve.now
- Posted on X by cve.now
Affected versions
- TOTOLINK A950RG
4.1.2cu.5268_B20221104
Evidence 6
- Advisory
- Advisory
- Advisory
- Advisory
- Exploit
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-121597
Is CVE-2026-121597 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 setAppEasyWizardConfig handler in cstecgi.cgi copies a rootSsid or apcliSsid value into a fixed-size stack buffer without checking its length. A value of 157 bytes or more overwrites the saved return address, which the advisory says can allow control-flow hijacking of the CGI process.Source: gist.github.com
Which versions are affected by CVE-2026-121597?
A950RG: version 4.1.2cu.5268_B20221104.Source: cve.now feed data
Am I affected, and how do I check?
The checked facts list firmware V4.1.2cu.5268_B20221104 of the TOTOLINK A950RG. The overflow needs a functionType value that selects the repeater branch and a rootSsid or apcliSsid of 157 bytes or longer. Compare the firmware version shown in the device's web admin pages with this build.Source: gist.github.com
How do I fix CVE-2026-121597?
The checked facts do not name a fixed firmware version, so no upgrade target can be given from them. Check TOTOLINK's support site for a newer A950RG firmware that addresses this issue.Source: gist.github.com
What if there's no patch?
The checked facts list no workaround. The overflow depends on the repeater branch and long SSID values, so avoiding the repeater setup path in the Easy Setup Wizard is the only limiting step the facts suggest, and it is not confirmed by the vendor.Source: gist.github.com