CVE-2026-28525
MediumCVSS 6.8Exploitation Probability (EPSS)
Low risk24th percentile - higher than 24% of all known CVEs
Summary
SWUpdate contains an integer underflow vulnerability in the multipart upload parser in mongoose_multipart.c that allows unauthenticated attackers to cause a denial of service by sending a crafted HTTP POST request to /upload with a malformed multipart boundary and controlled TCP stream timing. Attackers can trigger an integer underflow in the mg_http_multipart_continue_wait_for_chunk() function when the buffer length falls within a specific range, causing an out-of-bounds heap read past the allocated receive buffer to a local IPC socket.
Risk Assessment
The risk is that an unauthenticated attacker can remotely crash the system, potentially disrupting software update services and the entire device.
Recommendation
Immediately update SWUpdate to a version containing the fix for the integer underflow vulnerability in the multipart parser. Until the update is applied, restrict access to the /upload endpoint to trusted networks only.
Other vulnerabilities in SWUpdate
See all- CVE-2026-109399High
SWUpdate through 2026.05.1 contains an improper certificate validation vulnerability in crypto/swupdate_cms_verify_openssl.c that trusts untrusted X.509 certificates embedded in CMS SignedData for chain building. Attackers holding a signing key from a sibling intermediate under the same root can embed that intermediate in the signature to install malicious updates.
- CVE-2025-41259High
SWUpdate before 2026.05 is affected by a time-of-check time-of-use (TOCTOU) race condition that allows local unprivileged attackers to escalate privileges to root or install untrusted contents using a signed update.
Original NVD description (English source)
SWUpdate contains an integer underflow vulnerability in the multipart upload parser in mongoose_multipart.c that allows unauthenticated attackers to cause a denial of service by sending a crafted HTTP POST request to /upload with a malformed multipart boundary and controlled TCP stream timing. Attackers can trigger an integer underflow in the mg_http_multipart_continue_wait_for_chunk() function when the buffer length falls within a specific range, causing an out-of-bounds heap read past the allocated receive buffer to a local IPC socket.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS