Missing cryptographic key commitment in the Amazon S3 Encryption Client for Go may allow a user with write access to the S3 bucket to introduce a new EDK that decrypts to different plaintext when the encrypted data key is stored in an "inst…

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Missing cryptographic key commitment in the Amazon S3 Encryption Client for Go may allow a user with write access to the S3 bucket to introduce a new EDK that decrypts to different plaintext when the encrypted data key is stored in an "instruction file" instead of S3's metadata record. To mitigate this issue, upgrade Amazon S3 Encryption Client for Go to version 4.0 or later.

Source published

17 Dec 2025 20:20:27 UTC

Source modified

17 Dec 2025 21:31:45 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 5.3 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N

CVSS 4.0 · 6.0 CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Missing cryptographic key commitment in the Amazon S3 Encryption Client for Go may allow a user with write access to the S3 bucket to introduce a new EDK that decrypts to different plaintext when the encrypted data key is stored in an "instruction file" instead of S3's metadata record. To mitigate this issue, upgrade Amazon S3 Encryption Client for Go to version 4.0 or later.

Source published

Dec 17, 2025, 8:20:27 PM (timezone not stated)

Source modified

Dec 17, 2025, 9:31:45 PM (timezone not stated)

Observed here

11 Nov 2026 02:42:30 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 4.0 · 6.0 CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Missing cryptographic key commitment in the Amazon S3 Encryption Client for Go may allow a user with write access to the S3 bucket to introduce a new EDK that decrypts to different plaintext when the encrypted data key is stored in an "instruction file" instead of S3's metadata record. To mitigate this issue, upgrade Amazon S3 Encryption Client for Go to version 4.0 or later.

Source published

17 Dec 2025 21:15:53 UTC

Source modified

30 Sep 2026 23:10:00 UTC

Observed here

25 Oct 2026 01:17:29 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · ff89ba41-3aa1-4d27-914a-91399e9639e5 · Secondary · 6.0 CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS 3.1 · ff89ba41-3aa1-4d27-914a-91399e9639e5 · Secondary · 5.3 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N

## Summary S3 Encryption Client for Go 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 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: <= v3.1 ### 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 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: v4.0.0 or later. ## Workarounds There are no workarounds, please upgrade to the suggested version of S3EC. ## References If customers have any questions or comments about this advisory, Amazon S3 Encryption Client asks that they contact AWS Security through the issue reporting page or directly via email to [[email protected]](mailto:[email protected]). Please do not create a public GitHub issue.

Source published

18 Dec 2025 18:50:42 UTC

Source modified

22 Dec 2025 18:41:44 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Publisher rating · MODERATE

Amazon S3 Encryption Client has a Key Commitment Issue in github.com/aws/amazon-s3-encryption-client-go

Source published

22 Dec 2025 18:15:35 UTC

Source modified

3 Mar 2026 04:57:50 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.