CVE-2025-53690
CVE-2025-53690 is a security flaw in Sitecore products. Attackers can run their own code on Sitecore products. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 4 Sep 2025.[1]
Sitecore products is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. Sitecore has published a fix or advice.
Description
CISA calls it a deserialization of untrusted data in Sitecore Multiple Products. In its words: “Sitecore Experience Manager (XM), Experience Platform (XP), Experience Commerce (XC), and Managed Cloud contain a deserialization of untrusted data vulnerability involving the use of default machine keys. This flaw allows attackers to exploit exposed ASP.NET machine keys to achieve remote code execution.”[1]
The underlying weakness is deserialization of untrusted data (CWE-502), in MITRE’s list of common software weaknesses.[2]
It scores 9.0 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; Sitecore’s advisory has them[3]. CISA names the product as Sitecore Multiple Products.
Most families won’t have Sitecore products; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 4 Sep 2025, within a day of it being made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 25 Sep 2025 to fix it.[1]
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 61%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
Sitecore 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]
- Check whether you use it.Sitecore products is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
- Send this page to your IT person.Ask them to confirm it’s fixed, or not in use. CISA gave US government agencies until 25 Sep 2025 to fix it.
- If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.
You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 9.0.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[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 61%.[4] |
See also
Other Sitecore flaws
- CVE-2019-9875, Sitecore CMS and Experience Platform (XP): deserialization ·
- CVE-2019-9874, Sitecore CMS and Experience Platform (XP): deserialization ·
- CVE-2021-42237, Sitecore XP: remote command execution ·
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 ·
Added the same day
- CVE-2025-48543, Android Runtime: use-after-free ·
- CVE-2025-38352, Linux Kernel: time-of-check time-of-use (TOCTOU) race condition ·
Every Sitecore flaw on CISA’s list · Everything added in September 2025
References
- ^ Cybersecurity and Infrastructure Security Agency. “Sitecore Multiple Products Deserialization of Untrusted Data Vulnerability”. Known Exploited Vulnerabilities Catalog, added 4 Sep 2025.
- ^ National Institute of Standards and Technology. “CVE-2025-53690 Detail”. National Vulnerability Database, published 3 Sep 2025.
- ^ Sitecore. Advisories and fixes: support.sitecore.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.606, percentile 99.1, 31 Oct 2026.
- CVE Program. “CVE-2025-53690”. 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.