CVE-2021-23017
A security issue in nginx resolver was identified, which might allow an attacker who is able to forge UDP packets from the DNS server to cause 1-byte memory overwrite, resulting in worker process crash or potential other impact.
Vulnerability Summary
CVSS v3 Score
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L
CVSS v2 Score
AV:N/AC:M/Au:N/C:P/I:P/A:P
EPSS Score (Exploitation Probability)
This vulnerability has a 73.54% probability of being exploited in the next 30 days, ranking higher than 99% of all scored CVEs.
CWE Classification
Related Vulnerabilities
Same Weakness Type(CWE-193)
ImageMagick is free and open-source software used for editing and manipulating digital images. Versions prior to 7.1.2-0 and 6.9.13-26 have a heap buffer overflow in the `InterpretImageFilename` function. The issue stems from an off-by-one error that causes out-of-bounds memory access when processing format strings containing consecutive percent signs (`%%`). Versions 7.1.2-0 and 6.9.13-26 fix the issue.
GIMP PSP File Parsing Off-By-One Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of GIMP. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the parsing of PSP files. Crafted data in a PSP file can trigger an off-by-one error when calculating a location to write within a heap-based buffer. An attacker can leverage this vulnerability to execute code in the context of the current process. . Was ZDI-CAN-22097.
In Memcached before 1.6.22, an off-by-one error exists when processing proxy requests in proxy mode, if \n is used instead of \r\n.
An issue was discovered in the Linux kernel before 6.3.4. fs/ksmbd/connection.c in ksmbd has an off-by-one error in memory allocation (because of ksmbd_smb2_check_message) that may lead to out-of-bounds access.
Off-by-one Error in GitHub repository v2fly/v2ray-core prior to 4.44.0.
Similar SeverityHIGH
Improper link resolution before file access ('link following') in Microsoft Defender allows an authorized attacker to elevate privileges locally.
Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.
An Improper Input Validation in Ivanti EPMM before versions 12.6.1.1, 12.7.0.1, and 12.8.0.1 allows a remotely authenticated user with administrative access to achieve remote code execution.
OpenClaw before 2026.4.22 contains a server-side request forgery vulnerability in the Zalo plugin's sendPhoto function that fails to validate outbound photo URLs through the SSRF guard. Attackers can bypass SSRF protection by providing malicious photo URLs to the Zalo Bot API, enabling unauthorized access to internal resources.
OpenClaw before 2026.4.22 contains an exec allowlist analysis vulnerability allowing shell expansion hiding in unquoted heredoc bodies. Attackers can bypass allowlist validation by embedding shell expansion tokens in heredoc bodies to execute unapproved commands at runtime.
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