How severe is CVE-2021-28842?

CVE-2021-28842 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-28842 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (57th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-28842?

CVE-2021-28842 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-2021-28842?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-28842 published?

CVE-2021-28842 was published on 2021-08-10 and last updated on 2026-06-17.

CVE-2021-28842

CVE-2021-28842 is a high-severity vulnerability in Trendnet Tew-755ap Firmware with a CVSS 3.x base score of 7.5. 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-476.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 1% (57th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-476
Affected product: Trendnet Tew-755ap Firmware
Published: 2021-08-10
Last modified: 2026-06-17

Description

Null Pointer Deference vulnerability 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 os service by sending the POST request to apply_cgi via action do_graph_auth without login_name key.

Frequently asked questions

What is CVE-2021-28842?: Null Pointer Deference vulnerability 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 os service by sending the POST request to apply_cgi via action do_graph_auth without login_name key.
How severe is CVE-2021-28842?: CVE-2021-28842 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-28842 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (57th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-28842?: CVE-2021-28842 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-2021-28842?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-28842 published?: CVE-2021-28842 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…

All CVEs affecting Trendnet Tew-755ap Firmware →

Other CWE-476 (NULL Pointer Dereference) vulnerabilities

CVE-2022-36648 — Critical (CVSS 10.0): The hardware emulation in the of_dpa_cmd_add_l2_flood of rocker device model in QEMU, as used in 7.0.0 and earlier,…
CVE-2020-14500 — Critical (CVSS 10.0): Secomea GateManager all versions prior to 9.2c, An attacker can send a negative value and overwrite arbitrary data.
CVE-2010-2495 — Critical (CVSS 10.0): The pppol2tp_xmit function in drivers/net/pppol2tp.c in the L2TP implementation in the Linux kernel before 2.6.34 does…
CVE-2026-46195 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: smb: client: validate dacloffset before building…
CVE-2026-31657 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: batman-adv: hold claim backbone gateways by…
CVE-2026-31436 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: dmaengine: idxd: fix possible wrong descriptor…

Browse all CWE-476 (NULL Pointer Dereference) vulnerabilities →