CVE-2025-55182
CVE-2025-55182 is a security flaw in Meta React Server Components. Attackers can run their own code on Meta React Server Components from anywhere, without logging in. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 5 Dec 2025, and says ransomware gangs have used it.[1]
Meta React Server Components is in things households have, such as phones, computers, browsers and everyday apps, so the fix matters at home as much as at work. Meta has published a fix or advice.
Description
CISA calls it a remote code execution in Meta React Server Components. In its words: “Meta React Server Components contains a remote code execution vulnerability that could allow unauthenticated remote code execution by exploiting a flaw in how React decodes payloads sent to React Server Function endpoints. Please note CVE-2025-66478 has been rejected, but it is associated with CVE-2025- 55182.”[1]
The underlying weakness is deserialization of untrusted data (CWE-502), in MITRE’s list of common software weaknesses.[2]
It scores 10.0 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by the organisation that published the CVE using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; Meta’s advisory has them[3]. CISA names the product as Meta React Server Components.
Every device with Meta React Server Components needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 5 Dec 2025, 2 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 12 Dec 2025 to fix it.[1] CISA says ransomware gangs have used it.
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at over 99%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as automatable: attackers can run it against many targets at once.
CISA doesn’t say who was attacked, or how.
Fix
Meta has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.”[1]
- Update Meta React Server Components now.Install the latest update from Meta on every device that has it, and restart when asked. Then turn on automatic updates, so the next fix arrives on its own.
- If there’s no update, stop using it.CISA’s advice when a flaw being used in attacks has no fix is to stop using the product until it does.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 10.0.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks, noting that ransomware gangs have used it.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at over 99%.[4] |
See also
Other deserialization of untrusted data flaws
- CVE-2021-23758, Ajax.NET Professional: deserialization of untrusted data ·
- CVE-2026-63077, JetBrains TeamCity: deserialization of untrusted data ·
- CVE-2026-50522, Microsoft SharePoint: deserialization of untrusted data ·
- CVE-2026-58644, Microsoft SharePoint: deserialization of untrusted data ·
- CVE-2026-45659, Microsoft SharePoint Server: deserialization of untrusted data ·
References
- ^ Cybersecurity and Infrastructure Security Agency. “Meta React Server Components Remote Code Execution Vulnerability”. Known Exploited Vulnerabilities Catalog, added 5 Dec 2025.
- ^ National Institute of Standards and Technology. “CVE-2025-55182 Detail”. National Vulnerability Database, published 3 Dec 2025.
- ^ Meta. Advisories and fixes: react.dev, facebook.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.998, percentile 100.0, 31 Oct 2026.
- CVE Program. “CVE-2025-55182”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.