CVE-2018-25021: The TCP Server module in toxcore before 0.2.8 doesn't free the TCP priority queue under certain conditions, wh

Q: How do I fix CVE-2018-25021?

toxcore: upgrade to 0.2.8. Exact commands for each OS are on this page.

Q: Is CVE-2018-25021 being exploited?

CVE-2018-25021 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-2018-25021 affect?

CVE-2018-25021 affects toxcore. Severity is high (CVSS 7.5). The TCP Server module in toxcore before 0.2.8 doesn't free the TCP priority queue under certain conditions, which allows a remote attacker to exhaust the system's memory, causing a denial of service (DoS).

Q: How urgent is CVE-2018-25021?

Priority 57/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

HIGH 7.5REMOTEUPGRADE

CVE-2018-25021 is a high-severity flaw (CVSS 7.5) affecting toxcore. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The TCP Server module in toxcore before 0.2.8 doesn't free the TCP priority queue under certain conditions, which allows a remote attacker to exhaust the system's memory, causing a denial of service (DoS).

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	2.3% (top 16%)
CISA exploited list	No
Weakness	CWE-404
Published	2021-12-13
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: toktok

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

Am I affected?

Timeline

2021-12-13 01:15 UTCPublished CVE record published
2026-06-17 01:54 UTCUpdated Record last modified

toktok toxcore UPGRADE

Affected: < 0.2.8

Fixed in: 0.2.8

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 0.2.8 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade toxcore

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-2018-25021?

toxcore: upgrade to 0.2.8. Exact commands for each OS are on this page.

Is CVE-2018-25021 being exploited?

CVE-2018-25021 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-2018-25021 affect?

CVE-2018-25021 affects toxcore. Severity is high (CVSS 7.5). The TCP Server module in toxcore before 0.2.8 doesn't free the TCP priority queue under certain conditions, which allows a remote attacker to exhaust the system's memory, causing a denial of service (DoS).

How urgent is CVE-2018-25021?

Priority 57/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

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References

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