CVE-2026-28525: SWUpdate contains an integer underflow vulnerability in the multipart upload parser in mongoose_multipart.c th

Q: How do I fix CVE-2026-28525?

swupdate: upgrade to newer than 2025.12. Exact commands for each OS are on this page.

Q: Is CVE-2026-28525 being exploited?

CVE-2026-28525 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-28525 affect?

CVE-2026-28525 affects swupdate. Severity is medium (CVSS 6.8). 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 malforme

Q: How urgent is CVE-2026-28525?

Priority 35/100. Remotely exploitable, no login, no user action

Routine

MEDIUM 6.8REMOTEUPGRADE

CVE-2026-28525 is a medium-severity flaw (CVSS 6.8) affecting swupdate. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	6.8 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 76%)
CISA exploited list	No
Weakness	CWE-125, CWE-191
Published	2026-04-23
Last modified	2026-10-26

Publisher (CNA): VulnCheck · Vendor: swupdate

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-23 21:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

swupdate swupdate UPGRADE

Affected: <= 2025.12

Fixed in: newer than 2025.12

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy swupdate || rpm -q swupdate || swupdate --version

2. UPGRADE to newer than 2025.12 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade swupdate

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade swupdate

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-28525?

swupdate: upgrade to newer than 2025.12. Exact commands for each OS are on this page.

Is CVE-2026-28525 being exploited?

CVE-2026-28525 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-28525 affect?

CVE-2026-28525 affects swupdate. Severity is medium (CVSS 6.8). 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 malforme

How urgent is CVE-2026-28525?

Priority 35/100. Remotely exploitable, no login, no user action

References

← Back to latest CVEs