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CVE-2026-21697VulnerabilityPublished

CVE-2026-21697: rezmoss axios4go · Race Condition

Affects rezmoss axios4goSource CVE Database V5

0

Not known to be exploited · CVSS 8.2 High : upgrade to 0.6.4 soon.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 4.0 base score
8.2High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 34% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 0.6.4
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 7 Jan 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

What to do

Upgrade axios4go and github.com/rezmoss/axios4go to 0.6.4.

Affected software

ProductAffectedFixed in
rezmossaxios4goAffected
  • <0.6.4
Fixed in
  • 0.6.4
Gogithub.com/rezmoss/axios4gopkg:golang/github.com/rezmoss/axios4goOther threatsAffected
  • <0.6.4
Fixed in
  • 0.6.4

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

1. Upgrade axios4go to version 0.6.4 or later immediately to ensure the race condition is fixed. 2. Audit all Go applications using axios4go to identify concurrent HTTP client usage patterns, especially where different proxy or authentication configurations are applied per request. 3. Refactor code to avoid sharing mutable global HTTP client configurations across goroutines without proper synchronization primitives such as mutexes or by using separate client instances per configuration. 4. Implement rigorous testing for concurrent request handling to detect race conditions using Go's race detector tool. 5. Monitor application logs for anomalies in HTTP client behavior or unexpected credential exposure. 6. Educate development teams on safe concurrent programming practices in Go, emphasizing immutable or properly synchronized shared state. 7. Review and tighten access controls and network segmentation to limit exposure of vulnerable services until patched. 8. Maintain an inventory of all internal and third-party Go libraries to quickly identify and remediate similar concurrency issues.

Description

axios4go is a Go HTTP client library. Prior to version 0.6.4, a race condition vulnerability exists in the shared HTTP client configuration. The global `defaultClient` is mutated during request execution without synchronization, directly modifying the shared `http.Client`'s `Transport`, `Timeout`, and `CheckRedirect` properties. Impacted applications include that that use axios4go with concurrent requests (multiple goroutines, `GetAsync`, `PostAsync`, etc.), those where different requests use different proxy configurations, and those that handle sensitive data (authentication credentials, tokens, API keys). Version 0.6.4 fixes this issue.

References

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