Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-28377 is a high-severity Inadequate Encryption Strength (CWE-326) vulnerability in Grafana Tempo. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Brute Force (T1110); ranked at the 5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SC-13 (Cryptographic Protection) and SC-12 (Cryptographic Key Establishment and Management) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-28377 is a vulnerability in Grafana Tempo that exposes the S3 SSE-C encryption key in plaintext via the /status/config endpoint. This flaw affects Grafana Tempo instances configured to store trace data in S3 using SSE-C encryption, as the endpoint reveals the key used to protect that data. The issue, reported by william_goodfellow, carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N) and is associated with CWE-326.
Any unauthenticated attacker with network access to the vulnerable Grafana Tempo instance can exploit this by sending a request to the /status/config endpoint, obtaining the encryption key directly in plaintext. With the key, the attacker can then decrypt and access sensitive trace data stored in the target S3 bucket, leading to high confidentiality impact without requiring privileges, user interaction, or elevated complexity.
Grafana has issued a security advisory with further details at https://grafana.com/security/security-advisories/cve-2026-28377. Security practitioners should consult this advisory for recommended mitigations and patches.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-16424
Vulnerability Data
A vulnerability in Grafana Tempo exposes the S3 SSE-C encryption key in plaintext through the /status/config endpoint, potentially allowing unauthorized users to obtain the key used to encrypt trace data stored in S3. Thanks to william_goodfellow for reporting this vulnerability.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 12 hardening rules · 6 OS baselines
V11.4.2V14.1.2V14.2.4
Mitigating Controls (NIST 800-53 r5) AI
SC-13 requires selection and implementation of specific cryptographic algorithms and key lengths, directly preventing use of inadequate encryption strength.
SC-12 governs cryptographic key establishment and management, which can enforce sufficient key sizes and thereby reduce inadequate encryption strength.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Strong encryption is required to protect confidentiality of data-at-rest.
Strong encryption is required to protect confidentiality of data-in-transit.
Hardened baselines can enforce minimum cryptographic algorithm and key-length settings.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Requiring the organization to define and enforce minimum cryptographic strength prevents deployment of insufficient key lengths or weak ciphers that can be brute-forced.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
Oracle Linux 9 (1 rule)
- V-271756 OL 9 local disk partitions must implement cryptographic mechanisms to prevent unauthorized disclosure or modification of all information that requires at rest protection. prevents CWE-326
RHEL 8 (1 rule)
- V-230224 All RHEL 8 local disk partitions must implement cryptographic mechanisms to prevent unauthorized disclosure or modification of all information that requires at rest protection. prevents CWE-326
RHEL 9 (1 rule)
- V-257879 RHEL 9 local disk partitions must implement cryptographic mechanisms to prevent unauthorized disclosure or modification of all information that requires at rest protection. prevents CWE-326
Windows Server 2016 (1 rule)
- V-224843 Systems requiring data at rest protections must employ cryptographic mechanisms to prevent unauthorized disclosure and modification of the information at rest. prevents CWE-326