CVE-2026-22028: Preact, a lightweight web development framework, JSON serialization protection to prevent Virtual DOM elements

Q: How do I fix CVE-2026-22028?

preact: upgrade to 10.26.10, 10.27.3, 10.28.2. Exact commands for each OS are on this page.

Q: Is CVE-2026-22028 being exploited?

CVE-2026-22028 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-2026-22028 affect?

CVE-2026-22028 affects preact. Severity is medium (CVSS 6.1). Preact, a lightweight web development framework, JSON serialization protection to prevent Virtual DOM elements from being constructed from arbitrary JSON. A regression introduced in Preact 10.26.5 caused this protection to be softened. In a

Q: How urgent is CVE-2026-22028?

Priority 31/100. Public exploit reference

Routine

MEDIUM 6.1UPGRADE

CVE-2026-22028 is a medium-severity flaw (CVSS 6.1) affecting preact. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Preact, a lightweight web development framework, JSON serialization protection to prevent Virtual DOM elements from being constructed from arbitrary JSON. A regression introduced in Preact 10.26.5 caused this protection to be softened. In applications where values from JSON payloads are assumed to be strings and passed unmodified to Preact as children, a specially-crafted JSON payload could be constructed that would be incorrectly treated as a va

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.3% (top 80%)
CISA exploited list	No
Weakness	CWE-843
Published	2026-01-08
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: preactjs

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

Am I affected?

Timeline

2026-01-08 15:15 UTCPublished CVE record published
2026-06-17 10:19 UTCUpdated Record last modified

preactjs preact UPGRADE

Affected: >= 10.26.5 and < 10.26.10 · >= 10.27.0 and < 10.27.3 · >= 10.28.0 and < 10.28.2

Fixed in: 10.26.10, 10.27.3, 10.28.2

Safe to downgrade to: a release before 10.26.5

1. Check installed version

npm ls preact

2. UPGRADE to 10.26.10

npm install preact@">=10.26.10"

3. If no update is available yet, DOWNGRADE to a release before 10.26.5

npm view preact versions npm install preact@"<10.26.5"

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-2026-22028?

preact: upgrade to 10.26.10, 10.27.3, 10.28.2. Exact commands for each OS are on this page.

Is CVE-2026-22028 being exploited?

CVE-2026-22028 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-2026-22028 affect?

CVE-2026-22028 affects preact. Severity is medium (CVSS 6.1). Preact, a lightweight web development framework, JSON serialization protection to prevent Virtual DOM elements from being constructed from arbitrary JSON. A regression introduced in Preact 10.26.5 caused this protection to be softened. In a

How urgent is CVE-2026-22028?

Priority 31/100. Public exploit reference

References

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