# CVE-2025-14759: Amazon.Extensions.S3 — Fixed in 3.2.0 .NET NuGet Not in CISA KEV # CVE-2025-14759 — Amazon.Extensions.S3.Encr… [Fix: aws/amazon-s3-encryption-client-dotnet@6a0272c](https://github.com/aws/amazon-s3-encryption-client-dotnet/commit/6a0272c79347b2672eea599f73ee1a94d131e899) CVE-2025-14759 is a Broken Cryptographic Algorithm vulnerability in Amazon.Extensions.S3.Encryption. A fix is available for Amazon.Extensions.S3.Encryption — see the affected versions and patch details below. Amazon S3 Encryption Client for .NET has a Key Commitment Issue Also known as[GHSA-4v42-65r3-3gjx](/vulnerability/GHSA-4v42-65r3-3gjx) Published Dec 17, 2025 Updated Oct 28, 2026 Affected 1 pkg Patched 1 / 1 Exploits None indexed Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS) ## Exploitation Status ### No confirmed exploitation observed yet - CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment. Exploitation and automatability from CISA’s SSVC triage for CVE-2025-14759. ## EPSS Exploitation Probability [via FIRST.org ↗](https://www.first.org/epss/) 0.1%probability of exploitation in next 30 days Lower Risk0.00% Lower risk than most CVEs1th percentile — riskier than 1% of all scored CVEsHighest risk 0.00%0.20%0.40%0.61%0.0%0.1%May 26Sep 26Nov 26 Probability of exploitation in the next 30 days, from [FIRST.org EPSS](https://www.first.org/epss/). ## Real-World Exposure 1 pkg affected .NET`Amazon.Extensions.S3.Encryption` Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems. ## Description ### Summary S3 Encryption Client for .NET (S3EC) is an open-source client-side encryption library used to facilitate writing and reading encrypted records to S3. When the encrypted data key (EDK) is stored in an "Instruction File" instead of S3's metadata record, the EDK is exposed to an "Invisible Salamanders" attack ([https://eprint.iacr.org/2019/016](https://eprint.iacr.org/2019/016)), which could allow the EDK to be replaced with a new key. ### Impact #### Background - Key Commitment There is a cryptographic property whereby under certain conditions, a single ciphertext can be decrypted into 2 different plaintexts by using different encryption keys. To address this issue, strong encryption schemes use what is known as "key commitment", a process by which an encrypted message can only be decrypted by one key; the key used to originally encrypt the message. In older versions of S3EC, when customers are also using a feature called "Instruction File" to store EDKs, key commitment is not implemented because multiple EDKs could be associated to an underlying encrypted message object. For such customers an attack that leverages the lack of key commitment is possible. A bad actor would need two things to leverage this issue: (i) the ability to create a separate, rogue, EDK that will also decrypt the underlying object to produce desired plaintext, and (ii) permission to upload a new instruction file to the S3 bucket to replace the existing instruction file placed there by the user using the S3C. Any future attempt to decrypt the underlying encrypted message with the S3EC will unwittingly use the rogue EDK to produce a valid plaintext message. Impacted versions: <= 3.1.0 ### Patches Amazon S3 Encryption Client is introducing the concept of "key commitment" to S3EC where the EDK is cryptographically bound to the ciphertext in order to address this issue. In order to maintain compatibility for in-flight messages, the fix will be released in two versions. A code-compatible minor version that can read messages with key-commitment but not write them, and a new major version that can both read and write messages with key-commitment. For maximum safety customers are asked to upgrade to the latest major version: 4.0.0 or later. ### Workarounds There are no workarounds, please upgrade to the suggested version of S3EC. ### References If users have any questions or comments about this advisory, Amazon S3 Encryption Client asks that they contact AWS Security via the issue reporting page or directly via email to [aws-security@amazon.com](mailto:aws-security@amazon.com). Please do not create a public GitHub issue. ## Affected Packages 1 total 1 fixed Ecosystem Package Vulnerable range Fix .NETNuGet `Amazon.Extensions.S3.Encryption` all versions 3.2.0`dotnet add package Amazon.Extensions.S3.Encryption --version 3.2.0` ## Detection & mitigation playbook Open-source dependency 1. ### Detect Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Amazon.Extensions.S3.Encryption, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version. 2. ### Fix Update Amazon.Extensions.S3.Encryption to 3.2.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-14759 is resolved across your whole dependency graph. 3. ### Workarounds If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands. ## Frequently Asked Questions \## Summary S3 Encryption Client for .NET (S3EC) is an open-source client-side encryption library used to facilitate writing and reading encrypted records to S3. When the encrypted data key (EDK) is stored in an "Instruction File" instead of S3's metadata record, the EDK is exposed to an "Invisible Salamanders" attack (https://eprint.iacr.org/2019/016), which could allow the EDK to be replaced with a new key. ## Impact ### Background - Key Commitment There is a cryptographic property whereby under certain conditions, a single ciphertext can be decrypted into 2 different plaintexts by O3 Security · Impact-Aware SCA ### Is CVE-2025-14759 in your dependencies? Find it across NuGet, including transitive dependencies. [Scan my dependencies](/book-demo) [How O3 SCA works](/impact-aware-sca)