GHSA-m5vr-3m74-jwxp: typo3/cms-core (CVE-2020-15098)

Package	Ecosystem	Affected	Fixed in
typo3/cms-core	Packagist	>=9.0.0, <9.5.20 \|\| >=10.0.0, <10.4.6	9.5.20, 10.4.6
typo3/cms	Packagist	>=10.0.0, <10.4.6 \|\| >=9.0.0, <9.5.20	10.4.6, 9.5.20

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Affected versions of typo3/cms-core and typo3/cms are 9.0.0 up to but not including 9.5.20, and 10.0.0 up to but not including 10.4.6. An attacker who can use an internal verification mechanism to create valid HMAC-SHA1 checksums can inject arbitrary data, which can lead to privilege escalation or remote code execution in some attack chains; the attacker needs a valid backend user session or access to an Extbase plugin or module action, depending on the chain. Upgrade to typo3/cms-core or typo3/cms 9.5.20 or 10.4.6.

Written 3 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
8.8	High	3.1	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.022, the 82nd percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 14:25 UTC First seen by agentprime
31 Oct 2026, 14:25 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.