CVE-2021-43823: Side-channel attack in Sourcegraph

Severity: medium (CVSS 4.0 v2.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.9% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-12-13 · updated 2026-06-17
Weakness: CWE-200

Description

Sourcegraph is a code search and navigation engine. Sourcegraph prior to version 3.33.2 is vulnerable to a side-channel attack where strings in private source code could be guessed by an authenticated but unauthorized actor. This issue affects the Saved Searches and Code Monitoring features. A successful attack would require an authenticated bad actor to create many Saved Searches or Code Monitors to receive confirmation that a specific string exists. This could allow an attacker to guess formatted tokens in source code, such as API keys. This issue was patched in version 3.33.2 and any future versions of Sourcegraph. We strongly encourage upgrading to secure versions. If you are unable to, you may disable Saved Searches and Code Monitors.

Affected products

sourcegraph: before 3.33.2 — fixed in 3.33.2

How to fix

Upgrade to a fixed version: sourcegraph 3.33.2. Check the vendor advisory for mitigations.

References

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