Summary
S3 Encryption Client for Java 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.
Background - Key Commitment
There is a cryptographic property whereby under certain conditions, a single ciphertext could 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: <= v3.5
Workarounds
There are no workarounds, please upgrade to the suggested version of S3EC.
References
If users have any questions or comments about this advisory, S3 Encryption Client asks that they contact AWS Security via our issue reporting page or directly via email to [email protected]. Please do not create a public GitHub issue.
Impact
The application uses a cryptographic algorithm known to have weaknesses, such as MD5, SHA-1, or DES. Typical impact: compromised confidentiality or integrity of protected data.
CVE-2025-14763 has a CVSS score of 5.3 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.0.0); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
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 we are releasing the fix 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
Frequently Asked Questions
- What is CVE-2025-14763? CVE-2025-14763 is a medium-severity use of a broken or risky cryptographic algorithm vulnerability in software.amazon.encryption.s3:amazon-s3-encryption-client-java (maven), affecting versions < 4.0.0. It is fixed in 4.0.0. The application uses a cryptographic algorithm known to have weaknesses, such as MD5, SHA-1, or DES.
- How severe is CVE-2025-14763? CVE-2025-14763 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of software.amazon.encryption.s3:amazon-s3-encryption-client-java are affected by CVE-2025-14763? software.amazon.encryption.s3:amazon-s3-encryption-client-java (maven) versions < 4.0.0 is affected.
- Is there a fix for CVE-2025-14763? Yes. CVE-2025-14763 is fixed in 4.0.0. Upgrade to this version or later.
- Is CVE-2025-14763 exploitable, and should I be worried? Whether CVE-2025-14763 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-14763 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2025-14763? Upgrade
software.amazon.encryption.s3:amazon-s3-encryption-client-javato 4.0.0 or later.