CVE-2023-41101: An issue was discovered in the captive portal in OpenNDS before version 10.1.3

This month

CRITICAL 9.8REMOTEUPGRADE

CVE-2023-41101 is a critical-severity flaw (CVSS 9.8) affecting opennds. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in the captive portal in OpenNDS before version 10.1.3. get_query in http_microhttpd.c does not validate the length of the query string of GET requests. This leads to a stack-based buffer overflow in versions 9.x and earlier, and to a heap-based buffer overflow in versions 10.x and later. Attackers may exploit the issue to crash OpenNDS (Denial-of-Service condition) or to inject and execute arbitrary bytecode (Remote Code

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.9% (top 21%)
CISA exploited list	No
Weakness	CWE-787
Published	2023-11-17
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: opennds

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

Am I affected?

Timeline

2023-11-17 06:15 UTCPublished CVE record published
2026-06-17 06:20 UTCUpdated Record last modified

opennds opennds UPGRADE

Affected: >= 9.0.0 and < 10.1.3

Fixed in: 10.1.3

Safe to downgrade to: a release before 9.0.0

1. Check installed version

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

2. UPGRADE to 10.1.3 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade opennds

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 9.0.0 (Debian / Ubuntu)

apt-cache madison opennds sudo apt install opennds=<VERSION_BEFORE_9.0.0> sudo apt-mark hold opennds

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

dnf --showduplicates list opennds sudo dnf downgrade opennds-<VERSION_BEFORE_9.0.0> sudo dnf versionlock add opennds

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-2023-41101?

opennds: upgrade to 10.1.3. Exact commands for each OS are on this page.

Is CVE-2023-41101 being exploited?

CVE-2023-41101 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-2023-41101 affect?

CVE-2023-41101 affects opennds. Severity is critical (CVSS 9.8). An issue was discovered in the captive portal in OpenNDS before version 10.1.3. get_query in http_microhttpd.c does not validate the length of the query string of GET requests. This leads to a stack-based buffer overflow in versions 9.x and

How urgent is CVE-2023-41101?

Priority 59/100. Critical severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2024-25763 MEDIUM 5.5 DOWNGRADE openNDS 10.2.0 is vulnerable to Use-After-Free via /openNDS/src/auth.c.
CVE-2023-41102 HIGH 7.5 UPGRADE An issue was discovered in the captive portal in OpenNDS before version 10.1.3
CVE-2023-38323 CRITICAL 9.8 UPGRADE An issue was discovered in OpenNDS before 10.1.3
CVE-2023-38319 CRITICAL 9.8 UPGRADE An issue was discovered in OpenNDS before 10.1.3
CVE-2023-38318 CRITICAL 9.8 UPGRADE An issue was discovered in OpenNDS before 10.1.3

References

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