CVE-2022-34009: Fossil 2.18 on Windows allows attackers to cause a denial of service (daemon crash) via an XSS payload in a ti

Routine

MEDIUM 5.5DOWNGRADE

CVE-2022-34009 is a medium-severity flaw (CVSS 5.5) affecting fossil. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Fossil 2.18 on Windows allows attackers to cause a denial of service (daemon crash) via an XSS payload in a ticket. This occurs because the ticket data is stored in a temporary file, and the product does not properly handle the absence of this file after Windows Defender has flagged it as malware.

Why this priority

Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.5 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.4% (top 70%)
CISA exploited list	No
Weakness	CWE-79
Published	2022-07-28
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: fossil-scm

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

Am I affected?

Timeline

2022-07-28 00:15 UTCPublished CVE record published
2026-06-17 04:49 UTCUpdated Record last modified

fossil-scm fossil DOWNGRADE

Affected: 2.18

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.18

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2.18 (Debian / Ubuntu)

apt-cache madison fossil sudo apt install fossil=<VERSION_BEFORE_2.18> sudo apt-mark hold fossil

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list fossil sudo dnf downgrade fossil-<VERSION_BEFORE_2.18> sudo dnf versionlock add fossil

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-2022-34009?

fossil: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2022-34009 being exploited?

CVE-2022-34009 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-2022-34009 affect?

CVE-2022-34009 affects fossil. Severity is medium (CVSS 5.5). Fossil 2.18 on Windows allows attackers to cause a denial of service (daemon crash) via an XSS payload in a ticket. This occurs because the ticket data is stored in a temporary file, and the product does not properly handle the absence of t

How urgent is CVE-2022-34009?

Priority 32/100. Public exploit reference

Software pages

Windows vulnerabilities · Windows Defender vulnerabilities

Related CVEs

CVE-2021-36377 HIGH 7.5 UPGRADE MITIGATE Fossil before 2.14.2 and 2.15.x before 2.15.2 often skips the hostname check during TLS certificate validation
CVE-2020-24614 HIGH 8.8 UPGRADE MITIGATE Fossil before 2.10.2, 2.11.x before 2.11.2, and 2.12.x before 2.12.1 allows remote authenticated users to exec

References

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