Chrome: External Control of Assumed-Immutable Web Parameter
CVE-2025-7656 is a high-severity external control of assumed-immutable web parameter vulnerability in Chrome from Google, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists version 138.0.7204.157 as the first without the flaw, so updating Chrome to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 11.1% chance of exploitation within 30 days, which is in the top 4.01% of all scored CVEs.
EPSS places it among the vulnerabilities most likely to be exploited soon.
What to do
- Update Chrome to 138.0.7204.157 or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Chrome | 138.0.7204.157 up to, but not including, 138.0.7204.157 | 138.0.7204.157 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. Scored by CISA (ADP).
Official description
Integer overflow in V8 in Google Chrome prior to 138.0.7204.157 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page. (Chromium security severity: High)
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: External Control of Assumed-Immutable Web Parameter
The web application does not sufficiently verify inputs that are assumed to be immutable but are actually externally controllable, such as hidden form fields.
How developers prevent this class of flaw
- Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
More External Control of Assumed-Immutable Web Parameter vulnerabilities (CWE-472)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other references
- issues.chromium.org/issues/425583995Issue Tracking, Permissions Required
Other vulnerabilities in Chrome
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 7.5 High severity
Recent External Control of Assumed-Immutable Web Parameter vulnerabilities
- 8.8 High severity
- 5.3 Medium severity
- 7.5 High severity
- 8.6 High severity
- 7.5 High severity
- 8.8 High severity
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