CVE-2025-55763: Buffer Overflow in the URI parser of CivetWeb 1.14 through 1.16 (latest) allows a remote attacker to achieve r

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HIGH 7.5REMOTEUPGRADE

CVE-2025-55763 is a high-severity flaw (CVSS 7.5) affecting civetweb. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Buffer Overflow in the URI parser of CivetWeb 1.14 through 1.16 (latest) allows a remote attacker to achieve remote code execution via a crafted HTTP request. This vulnerability is triggered during request processing and may allow an attacker to corrupt heap memory, potentially leading to denial of service or arbitrary code execution.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.2% (top 32%)
CISA exploited list	No
Weakness	CWE-121
Published	2025-08-29
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: civetweb project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-08-29 17:15 UTCPublished CVE record published
2026-06-17 09:42 UTCUpdated Record last modified

civetweb project civetweb UPGRADE

Affected: >= 1.14 and <= 1.16

Fixed in: newer than 1.16

Safe to downgrade to: a release before 1.14

1. Check installed version

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

2. UPGRADE to newer than 1.16 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade civetweb

Note

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

3. If no update is available yet, DOWNGRADE to a release before 1.14 (Debian / Ubuntu)

apt-cache madison civetweb sudo apt install civetweb=<VERSION_BEFORE_1.14> sudo apt-mark hold civetweb

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list civetweb sudo dnf downgrade civetweb-<VERSION_BEFORE_1.14> sudo dnf versionlock add civetweb

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

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-2025-55763?

civetweb: upgrade to newer than 1.16. Exact commands for each OS are on this page.

Is CVE-2025-55763 being exploited?

CVE-2025-55763 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-2025-55763 affect?

CVE-2025-55763 affects civetweb. Severity is high (CVSS 7.5). Buffer Overflow in the URI parser of CivetWeb 1.14 through 1.16 (latest) allows a remote attacker to achieve remote code execution via a crafted HTTP request. This vulnerability is triggered during request processing and may allow an attack

How urgent is CVE-2025-55763?

Priority 53/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-5789 HIGH 7.8 DOWNGRADE Vulnerability related to an unquoted search path in CivetWeb v1.16
CVE-2020-27304 CRITICAL 9.8 UPGRADE UPGRADE The CivetWeb web library does not validate uploaded filepaths when running on an OS other than Windows, when u

References

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