An information disclosure vulnerability exists in how Microsoft Exchange validates tokens when handling certain messages. An attacker who successfully exploited the vulnerability could use this to gain further information from a user.
To exploit the vulnerability, an attacker could include specially crafted OWA messages that could be loaded, without warning or filtering, from the attacker-controlled URL. This callback vector provides an information disclosure tactic used in web beacons and other types of tracking systems.
The security update corrects the way that Exchange handles these token validations.
## Which versions are affected by CVE-2020-16969? It affects 1 product. Products: Microsoft Exchange Server. ## How do I fix CVE-2020-16969? No fix has been published for CVE-2020-16969 yet. Limit exposure of the affected software until one is available. ## Is CVE-2020-16969 being exploited? There is no known exploitation of CVE-2020-16969 in the wild and no public exploit code. ## Other vulnerabilities in Microsoft Exchange Server - [CVE-2024-21410](https://insights.sbomify.com/CVE-2024-21410/): Microsoft Exchange Server Privilege Escalation (critical 9.8, exploited in the wild) - [CVE-2021-34473](https://insights.sbomify.com/CVE-2021-34473/): Microsoft Exchange Server Remote Code Execution (critical 9.1, exploited in the wild) - [CVE-2021-26855](https://insights.sbomify.com/CVE-2021-26855/): Microsoft Exchange Server Remote Code Execution (critical 9.1, exploited in the wild) - [CVE-2021-34523](https://insights.sbomify.com/CVE-2021-34523/): Microsoft Exchange Server Privilege Escalation (critical 9.0, exploited in the wild) - [CVE-2023-21529](https://insights.sbomify.com/CVE-2023-21529/): Microsoft Exchange Server Deserialization of Untrusted Data (high 8.8, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2020-16969 and fix it if it is affected. What it is: CVE-2020-16969 is a high-severity vulnerability in Microsoft Exchange Server, published on 16 Oct 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link. Exploitation: There is no known exploitation of CVE-2020-16969 in the wild and no public exploit code. Affected product: Microsoft Exchange Server. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2020-16969/ (Markdown: https://insights.sbomify.com/CVE-2020-16969/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2020-16969 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-16969 - OSV: https://osv.dev/vulnerability/CVE-2020-16969 --- From sbomify Insights: https://insights.sbomify.com/CVE-2020-16969/ Summaries are generated and may contain mistakes; the official description above is the record.