CVE-2026-28377 S3 SSE-C Encryption Key Exposed in Plaintext via Config Endpoint (CVE-2025-41118 Pattern)
Attackers can retrieve S3 SSE-C encryption keys from the status config endpoint, exposing encrypted trace data.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-28377?
CVE-2026-28377 is a high-severity vulnerability in Grafana Tempo, published on 26 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-326
Which versions are affected by CVE-2026-28377?
3 open source packages ship an affected version, including github.com/grafana/tempo. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/grafana/tempo Go | All versions | None |
github.com/grafana/tempo Go | All versions | 2.10.3 |
github.com/grafana/tempo Go | All versions | 2.10.3 |
Linux distribution packages (1)
tempo-cli openSUSE:Tumbleweed | All versions | 2.10.3-1.1 |
Products include Grafana Tempo.
How do I fix CVE-2026-28377?
Upgrade github.com/grafana/tempo to 2.10.3 or later.
Is CVE-2026-28377 being exploited?
There is no known exploitation of CVE-2026-28377 in the wild and no public exploit code.
Other vulnerabilities in Grafana Tempo
Sources
Also known as CLEANSTART-2026-IH60054, CLEANSTART-2026-LM45189, CLEANSTART-2026-MG98376, CLEANSTART-2026-VL81811, ECHO-69d9-d5a1-7d86, GHSA-ffqx-q65f-36jf and 20 more.