Is CVE-2026-55785 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-55785 being exploited in the wild.

How severe is CVE-2026-55785?

Low severity, with a CVSS score of 3.7, published 28 August 2026.

Which products and versions are affected?

github.com/free5gc/ausf (Go) < 1.4.5, SEMVER:introduced=0,fixed=1.4.5.

Is there a fix for CVE-2026-55785?

Yes. github.com/free5gc/ausf (Go): upgrade to 1.4.5 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-55785 attacked?

It is attacked over the network or with local access.

Am I affected by CVE-2026-55785?

Check whether you run github.com/free5gc/ausf (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-55785: free5GC AUSF non-constant-time authentication comparison and sensitive logging

Q: Is there a fix for CVE-2026-55785?

Yes. github.com/free5gc/ausf (Go): upgrade to 1.4.5 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Q: How is CVE-2026-55785 attacked?

It is attacked over the network or with local access.

Q: Am I affected by CVE-2026-55785?

Check whether you run github.com/free5gc/ausf (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-55785 · Severity: low · CVSS 3.7 · Published 2026-08-28

free5GC's AUSF (Authentication Server Function) component handles 5G network user authentication using cryptographic protocols. The component compares authentication response values using non-constant-time comparison functions and logs sensitive authentication credentials (XRES*) to application logs. While timing attacks over the network were not practically demonstrated in testing, the direct exposure of authentication material in logs creates a risk if logs are accessible to operators, infrastructure systems, or log aggregation platforms.

Technologies: github.com/free5gc/ausf (Go). Vendors: Go.

Quick answers

Is CVE-2026-55785 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-55785 being exploited in the wild.
How severe is CVE-2026-55785?: Low severity, with a CVSS score of 3.7, published 28 August 2026.
Which products and versions are affected?: github.com/free5gc/ausf (Go) < 1.4.5, SEMVER:introduced=0,fixed=1.4.5.
Is there a fix for CVE-2026-55785?: Yes. github.com/free5gc/ausf (Go): upgrade to 1.4.5 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-55785 attacked?: It is attacked over the network or with local access.
Am I affected by CVE-2026-55785?: Check whether you run github.com/free5gc/ausf (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

github.com/free5gc/ausf (Go): upgrade to 1.4.5 or later
```
go get github.com/free5gc/ausf@v1.4.5
```

Technical details

The vulnerability consists of two issues in `internal/sbi/processor/ue_authentication.go`. First, the 5G-AKA authentication confirmation path uses `strings.EqualFold()` to compare RES* and XRES* values—a non-constant-time string comparison that may return early on mismatch. More critically, XRES* (the expected authentication response) is logged at INFO level immediately before comparison, exposing authentication material to any process or system with log access. Second, the EAP-AKA' confirmation path uses `bytes.Equal()` and string `==` comparison for MAC and response values instead of `crypto/subtle.ConstantTimeCompare()`. Lab testing confirmed that timing signal at the comparator level is masked by HTTP/SBI network noise, making remote timing attacks impractical. However, local CPU benchmarks show the non-constant-time behavior is real (0.31 ns delta), and the logging of XRES* is directly observable and exploitable. Fixed in v1.4.5 with constant-time comparisons and removal of sensitive values from logs.

Affected products

github.com/free5gc/ausf (Go) < 1.4.5, SEMVER:introduced=0,fixed=1.4.5

Identifiers

CVE-2026-55785
GHSA-fp46-6vfw-gc9c
GO-2026-6328

Timeline

2026-06-22: disclosed: GitHub Advisory published
2026-06-22: patched: v1.4.5 released with fix
2026-08-28: advisory

References

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