# What is CVE-2021-42029? > CVE-2021-42029 is a high-severity flaw (CVSS 7.8) in Simatic Step 7 from Siemens, published on 12 April 2022. It is not on the list of flaws known to be exploited today. The latest forecast puts its chance of use in the next 30 days at 0.2%. If you run an affected version, plan in the vendor’s fix. Canonical page: https://www.precursorintelligence.com/what-is/cve-2021-42029 ## At a glance - **Verdict:** Plan it in. No sign of exploitation and a low forecast. Patch it in your normal update cycle. - **Precursor Intelligence risk score:** 47 out of 100 (Medium); action: Plan remediation. Kept up to date as the evidence changes. - **Severity:** High (CVSS 7.8 out of 10) - **Known to be exploited:** No, not on the list of flaws known to be exploited today - **Chance of use in the next 30 days:** 0.2% (latest exploit-likelihood forecast) - **Published:** 12 April 2022 - **Record last updated:** 9 August 2022 - **Main product:** Simatic Step 7 from Siemens - **Affected products:** 71 ## What is CVE-2021-42029? In plain terms An attacker has to be already on the device with an ordinary user account, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline. ### The official description A vulnerability has been identified in SIMATIC STEP 7 (TIA Portal) V15 (All versions), SIMATIC STEP 7 (TIA Portal) V16 (All versions < V16 Update 5), SIMATIC STEP 7 (TIA Portal) V17 (All versions < V17 Update 2). An attacker could achieve privilege escalation on the web server of certain devices due to improper access control vulnerability in the engineering system software. The attacker needs to have direct access to the impacted web server. ### What kind of flaw is it? - CWE-284: Improper Access Control ### How an attack on it works - Where an attacker can be: Already on the device - How hard it is to pull off: Easy: no special conditions - Login needed first: An ordinary user account - Does someone have to click: No, nobody has to do anything - What an attacker gets: Can read data, change data and take it offline Severity vector: `CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H` ## Is CVE-2021-42029 being exploited? Not that we know of It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 0.2%. That can change at any time, which is why we keep watching. Exploit likelihood over the last 7 days: 0.2%, 0.2%, 0.2%, 0.2%, 0.2%, 0.2%, 0.2%. ### Timeline - 12 April 2022: Published - 9 August 2022: Record last updated ### How Precursor Intelligence ranks it CVE-2021-42029 scores **47 out of 100 (Medium)**, with the action "Plan remediation". Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less: - Evidence it is being exploited: biggest factor - How severe it is: strong factor - How widely exposed it is: smaller factor - Threat activity around it: smaller factor 85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it. ## Who is affected by CVE-2021-42029? The published record lists 71 products. Versions are as published: "15 to before 16" means from 15 up to, but not including, 16. - [Simatic Step 7](https://www.precursorintelligence.com/product/siemens/simatic_step_7) by [Siemens](https://www.precursorintelligence.com/vendors/siemens) (Application): 15 to before 16, 16, 16-update1, 16-update2, 16-update3, 16-update4, 17, 17-update1 - [Simatic S7-1200 CPU](https://www.precursorintelligence.com/product/siemens/simatic_s7-1200_cpu) by [Siemens](https://www.precursorintelligence.com/vendors/siemens) (Hardware): version not specified - [Simatic S7-1200 CPU 1211c](https://www.precursorintelligence.com/product/siemens/simatic_s7-1200_cpu_1211c) by [Siemens](https://www.precursorintelligence.com/vendors/siemens) (Hardware): version not specified - [Simatic S7-1200 CPU 1212c](https://www.precursorintelligence.com/product/siemens/simatic_s7-1200_cpu_1212c) by [Siemens](https://www.precursorintelligence.com/vendors/siemens) (Hardware): version not specified - [Simatic S7-1200 CPU 1212fc](https://www.precursorintelligence.com/product/siemens/simatic_s7-1200_cpu_1212fc) by [Siemens](https://www.precursorintelligence.com/vendors/siemens) (Hardware): version not specified - 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Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list. 2. **Apply the vendor’s fix.** Install the update named in the vendor’s advisory. We’ve put the advisory first in the list. 3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in. 4. **Keep an eye on it.** Track the product and we tell you as soon as we spot this flaw on the list of exploited flaws, or a jump in its exploit likelihood. ### References - [cert-portal.siemens.com](https://cert-portal.siemens.com/productcert/pdf/ssa-350757.pdf) (Patch, Vendor advisory) ## Questions ### What is CVE-2021-42029? CVE-2021-42029 is a high-severity flaw in Simatic Step 7 from Siemens, published on 12 April 2022. An attacker has to be already on the device with an ordinary user account, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline. ### How serious is CVE-2021-42029? It scores 7.8 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2021-42029 is 47 out of 100, which is Medium. Its action is "Plan remediation". No sign of exploitation and a low forecast. Patch it in your normal update cycle. ### Is CVE-2021-42029 being exploited? It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 0.2%. That can change at any time, which is why we keep watching. ### Which versions does CVE-2021-42029 affect? For Simatic Step 7 from Siemens: 15 to before 16, 16, 16-update1, 16-update2, 16-update3, 16-update4 and 2 more. The record lists 71 products in all, each with its versions, under "Who is affected" on this page. ### How do I fix CVE-2021-42029? Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet. ## Does CVE-2021-42029 affect you? Precursor Intelligence keeps checking for you: - **Tell us what you run.** Pick your software from a list, or let us work it out from your website. - **We match it to every flaw.** Over 400,000 published flaws, checked against your list. - **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it. - **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools. Start free (no card, nothing to install): https://www.precursorintelligence.com/register Book a demo: https://www.precursorintelligence.com/contact