How severe is CVE-2021-28844?

CVE-2021-28844 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-2021-28844 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-2021-28844?

CVE-2021-28844 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-2021-28844?

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-2021-28844 published?

CVE-2021-28844 was published on 2021-08-10 and last updated on 2026-06-17.

CVE-2021-28844

CVE-2021-28844 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 Dereference vulnerability exists in TRENDnet TEW-755AP 1.11B03, TEW-755AP2KAC 1.11B03, TEW-821DAP2KAC 1.11B03, and TEW-825DAP 1.11B03 by sending the POST request to apply_cgi via a do_graph_auth action without a session_id key.

Frequently asked questions

What is CVE-2021-28844?: Null Pointer Dereference vulnerability exists in TRENDnet TEW-755AP 1.11B03, TEW-755AP2KAC 1.11B03, TEW-821DAP2KAC 1.11B03, and TEW-825DAP 1.11B03 by sending the POST request to apply_cgi via a do_graph_auth action without a session_id key.
How severe is CVE-2021-28844?: CVE-2021-28844 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-2021-28844 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-2021-28844?: CVE-2021-28844 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-2021-28844?: 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-2021-28844 published?: CVE-2021-28844 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

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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 →