Router: Predictable Seed in Pseudo-Random Number Generator (PRNG)
CVE-2026-19396 is a high-severity predictable seed in pseudo-random number generator (PRNG) vulnerability in Router from ASUS, with a CVSS 4.0 base score of 7.7 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. Affected Router versions: 3.0.0.6_102 series. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.13% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of Router you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on asus.com for workarounds and exact fixed builds.
Affected products and versions
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
- AdjacentThe attacker must be on the same local network segment.
- Attack complexity
- HighSuccess depends on conditions outside the attacker's control.
- Attack requirements
- PresentThe target must be in a specific state or configuration for the attack to work.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Confidentiality (vulnerable system)
- HighSerious loss of confidentiality on the vulnerable system.
- Integrity (vulnerable system)
- HighSerious loss of integrity on the vulnerable system.
- Availability (vulnerable system)
- HighSerious loss of availability on the vulnerable system.
- Confidentiality (other systems)
- NoneNo loss of confidentiality on systems beyond the vulnerable one.
- Integrity (other systems)
- NoneNo loss of integrity on systems beyond the vulnerable one.
- Availability (other systems)
- NoneNo loss of availability on systems beyond the vulnerable one.
Vector: CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. Scored by CNA.
Official description
A predictable seed in the pseudo-random number generator (PRNG) in the IFTTT pairing token generation of the ASUS RT-BE57 router allows an unauthenticated nearby user to derive the pairing token and read or modify router settings via observed values from an administrator-initiated IFTTT pairing session.Refer to the ' Security Update for ASUS Router Firmware ' section on the ASUS Security Advisory for more information.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Predictable Seed in Pseudo-Random Number Generator (PRNG)
A Pseudo-Random Number Generator (PRNG) is initialized from a predictable seed, such as the process ID or system time.
How developers prevent this class of flaw
- Use non-predictable inputs for seed generation.
- Use products or modules that conform to FIPS 140-2 to avoid obvious entropy problems, or use the more recent FIPS 140-3 if possible.
- Use a PRNG that periodically re-seeds itself using input from high-quality sources, such as hardware devices with high entropy. However, do not re-seed too frequently, or else the entropy source might block.
More Predictable Seed in Pseudo-Random Number Generator (PRNG) vulnerabilities (CWE-337)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
References
Advisories
Other vulnerabilities in Router
- 8.7 High severity
- 8.6 High severity
- 7.7 High severity
- 8.2 High severity
- 9.3 Critical severity
- 9.3 Critical severity
Recent Predictable Seed in Pseudo-Random Number Generator (PRNG) vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 8.3 High severity
- 8.7 High severity
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