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fix(core): Find the correct IP address regardless their case #18880

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Merged
JPeer264 merged 1 commit into from
Jan 19, 2026
Merged

fix(core): Find the correct IP address regardless their case #18880

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10 changes: 9 additions & 1 deletion packages/core/src/vendor/getIpAddress.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -52,10 +52,18 @@ export const ipHeaderNames = [
* will be returned.
*/
export function getClientIPAddress(headers: { [key: string]: string | string[] | undefined }): string | null {
// Build a map of lowercase header names to their values for case-insensitive lookup
// This is needed because headers from different sources may have different casings
const lowerCaseHeaders: { [key: string]: string | string[] | undefined } = {};

for (const key of Object.keys(headers)) {
lowerCaseHeaders[key.toLowerCase()] = headers[key];
}

// This will end up being Array<string | string[] | undefined | null> because of the various possible values a header
// can take
const headerValues = ipHeaderNames.map((headerName: string) => {
const rawValue = headers[headerName];
const rawValue = lowerCaseHeaders[headerName.toLowerCase()];
const value = Array.isArray(rawValue) ? rawValue.join(';') : rawValue;

if (headerName === 'Forwarded') {
Comment on lines +59 to 69
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@sentry sentry bot Jan 19, 2026

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Bug: The new case-insensitive IP header reading is not matched by the deletion logic, which remains case-sensitive, potentially leaking IP headers when PII stripping is enabled.
Severity: CRITICAL

Suggested Fix

Modify the header deletion logic in extractNormalizedRequestData() to be case-insensitive. This can be achieved by iterating over the actual request headers, converting each to lowercase, and checking if it exists in a pre-computed set of lowercase IP header names before deletion. This ensures symmetry between reading and removing IP-related headers.

Prompt for AI Agent 
Review the code at the location below. A potential bug has been identified by an AI
agent.
Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not
valid.

Location: packages/core/src/vendor/getIpAddress.ts#L52-L69

Potential issue: The pull request updates `getClientIPAddress()` to read IP-related
headers in a case-insensitive manner. However, the corresponding logic in
`extractNormalizedRequestData()` for removing these headers when `sendDefaultPii` is
`false` remains case-sensitive. It iterates through `ipHeaderNames` and performs an
exact-match deletion. This creates a situation where a header like `Cf-Connecting-Ip`
will be correctly identified as containing an IP address but will not be deleted if PII
stripping is enabled. This results in the unintended leakage of IP address information
in events.

Did we get this right? 👍 / 👎 to inform future reviews.

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9 changes: 9 additions & 0 deletions packages/core/test/lib/vendor/getClientIpAddress.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -29,4 +29,13 @@ describe('getClientIPAddress', () => {

expect(ip).toEqual(expectedIP);
});

it('should find headers regardless of case', () => {
const headers = {
'Cf-Connecting-Ip': '1.1.1.1',
};

const ip = getClientIPAddress(headers);
expect(ip).toEqual('1.1.1.1');
});
});
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