How severe is CVE-2021-28846?

CVE-2021-28846 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-28846 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-28846?

CVE-2021-28846 primarily affects Trendnet Tew-755ap Firmware. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-28846?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-28846 published?

CVE-2021-28846 was published on 2021-08-10 and last updated on 2026-06-17.

CVE-2021-28846

CVE-2021-28846 is a medium-severity vulnerability in Trendnet Tew-755ap Firmware with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-134.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.0
EPSS exploit prediction: 1% (53rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-134
Affected product: Trendnet Tew-755ap Firmware
Published: 2021-08-10
Last modified: 2026-06-17

Description

A Format String vulnerablity exists in TRENDnet TEW-755AP 1.11B03, TEW-755AP2KAC 1.11B03, TEW-821DAP2KAC 1.11B03, and TEW-825DAP 1.11B03, which could let a remote malicious user cause a denial of service due to a logic bug at address 0x40dcd0 when calling fprintf with "%s: key len = %d, too long\n" format. The two variables seem to be put in the wrong order. The vulnerability could be triggered by sending the POST request to apply_cgi with a long and unknown key in the request body.

Frequently asked questions

What is CVE-2021-28846?: A Format String vulnerablity exists in TRENDnet TEW-755AP 1.11B03, TEW-755AP2KAC 1.11B03, TEW-821DAP2KAC 1.11B03, and TEW-825DAP 1.11B03, which could let a remote malicious user cause a denial of service due to a logic bug at address 0x40dcd0 when calling fprintf with "%s: key len = %d, too long\n" format. The two variables seem to be put in the wrong order. The vulnerability could be triggered by sending the POST request to apply_cgi with a long and unknown key in the request body.
How severe is CVE-2021-28846?: CVE-2021-28846 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-28846 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-28846?: CVE-2021-28846 primarily affects Trendnet Tew-755ap Firmware. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-28846?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-28846 published?: CVE-2021-28846 was published on 2021-08-10 and last updated on 2026-06-17.

References

https://github.com/zyw-200/EQUAFL/blob/main/TRENDnet%20ticket.pdf

Affected products (4)

cpe:2.3:o:trendnet:tew-755ap_firmware:1.11b03:*:*:*:*:*:*:*
cpe:2.3:o:trendnet:tew-755ap2kac_firmware:1.11b03:*:*:*:*:*:*:*
cpe:2.3:o:trendnet:tew-821dap2kac_firmware:1.11b03:*:*:*:*:*:*:*
cpe:2.3:o:trendnet:tew-825dap_firmware:1.11b03:*:*:*:*:*:*:*

More vulnerabilities in Trendnet Tew-755ap Firmware

CVE-2022-46601 — Critical (CVSS 9.8): TRENDnet TEW755AP 1.13B01 was discovered to contain a stack overflow via the setbg_num parameter in the icp_setbg_img…
CVE-2022-46600 — Critical (CVSS 9.8): TRENDnet TEW755AP 1.13B01 was discovered to contain a stack overflow via the wps_sta_enrollee_pin parameter in the…
CVE-2022-46599 — Critical (CVSS 9.8): TRENDnet TEW755AP 1.13B01 was discovered to contain a stack overflow via the setlogo_num parameter in the…
CVE-2022-46598 — Critical (CVSS 9.8): TRENDnet TEW755AP 1.13B01 was discovered to contain a command injection vulnerability via the wps_sta_enrollee_pin…
CVE-2022-46597 — Critical (CVSS 9.8): TRENDnet TEW755AP 1.13B01 was discovered to contain a command injection vulnerability via the sys_service parameter in…
CVE-2022-46596 — Critical (CVSS 9.8): TRENDnet TEW755AP 1.13B01 was discovered to contain a stack overflow via the del_num parameter in the icp_delete_img…

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Other CWE-134 vulnerabilities

CVE-2012-1851 — Critical (CVSS 10.0): Format string vulnerability in the Print Spooler service in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2,…
CVE-2012-0242 — Critical (CVSS 10.0): Format string vulnerability in Advantech/BroadWin WebAccess before 7.0 allows remote attackers to execute arbitrary…
CVE-2011-2475 — Critical (CVSS 10.0): Format string vulnerability in ECTrace.dll in the iMailGateway service in the Internet Mail Gateway in OneBridge Server…
CVE-2011-1568 — Critical (CVSS 10.0): Format string vulnerability in the logText function in shmemmgr9.dll in IGSSdataServer.exe 9.00.00.11074, and…
CVE-2010-4235 — Critical (CVSS 10.0): Format string vulnerability in RealNetworks Helix Server 12.x, 13.x, and 14.x before 14.2, and Helix Mobile Server…
CVE-2011-0270 — Critical (CVSS 10.0): Format string vulnerability in nnmRptConfig.exe in HP OpenView Network Node Manager (OV NNM) 7.51 and 7.53 allows…

Browse all CWE-134 vulnerabilities →