Axios: Header Injection via Inherited headers After Minimal Interceptor

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Axios is a promise-based HTTP client for the browser and Node.js. From 1.0.0 until 1.20.0, the dispatchRequest function normalizes inherited Object.prototype.headers from a replacement request configuration. A separate same-process prototype-pollution flaw sets Object.prototype.headers, and trusted request interceptors return a new ordinary configuration without an own headers property. After the interceptor chain, dispatchRequest resolves the inherited headers during normalization. Downstream request processing can observe attacker-controlled headers, including authorization-related values. This issue is fixed in version 1.20.0.

Source published

28 Sep 2026 17:29:10 UTC

Source modified

28 Sep 2026 17:49:57 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 4.0 · 6.9 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:H/SA:N

Axios is a promise-based HTTP client for the browser and Node.js. From 1.0.0 until 1.20.0, the dispatchRequest function normalizes inherited Object.prototype.headers from a replacement request configuration. A separate same-process prototype-pollution flaw sets Object.prototype.headers, and trusted request interceptors return a new ordinary configuration without an own headers property. After the interceptor chain, dispatchRequest resolves the inherited headers during normalization. Downstream request processing can observe attacker-controlled headers, including authorization-related values. This issue is fixed in version 1.20.0.

Source published

Sep 28, 2026, 5:29:10 PM (timezone not stated)

Source modified

Sep 28, 2026, 5:49:57 PM (timezone not stated)

Observed here

11 Nov 2026 05:28:14 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 4.0 · 6.9 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:H/SA:N

Axios is a promise-based HTTP client for the browser and Node.js. From 1.0.0 until 1.20.0, the dispatchRequest function normalizes inherited Object.prototype.headers from a replacement request configuration. A separate same-process prototype-pollution flaw sets Object.prototype.headers, and trusted request interceptors return a new ordinary configuration without an own headers property. After the interceptor chain, dispatchRequest resolves the inherited headers during normalization. Downstream request processing can observe attacker-controlled headers, including authorization-related values. This issue is fixed in version 1.20.0.

Source published

28 Sep 2026 18:17:18 UTC

Source modified

30 Sep 2026 19:38:27 UTC

Observed here

25 Oct 2026 04:17:26 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 6.9 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:H/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

## Summary Axios request interceptors may return a replacement config object. If an interceptor returns a plain object without an own `headers` property, `dispatchRequest()` later evaluates `config.headers` and can resolve an inherited `Object.prototype.headers` value. In a process where another vulnerability has polluted `Object.prototype.headers`, axios can send attacker-controlled headers. Axios does not create the prototype pollution source, and the interceptor itself is trusted caller code. The vulnerable behavior is the post-interceptor axios config read that reopens a prototype-pollution gadget after earlier null-prototype config hardening. ## Impact An attacker with a prior same-process prototype-pollution primitive can inject headers into affected axios requests when the application uses an interceptor that rebuilds config and omits headers. Depending on the target service, injected headers can affect cache behavior, conditional requests, metadata services, or application-specific authorization and routing logic. The issue is conditional and should not be described as affecting every interceptor or every request. ## Affected Functionality Affected: - Request interceptor chains where an interceptor returns a new ordinary object. - Replacement config objects that omit an own `headers` property. - `dispatchRequest()` header normalization through `AxiosHeaders.from(config.headers)`. Not affected: - Requests whose interceptor preserves an own `headers` property. - Interceptors that mutate and return the existing null-prototype config. - Processes without prototype pollution. ## Technical Details `lib/core/dispatchRequest.js` contains: ```js config.headers = AxiosHeaders.from(config.headers); ``` The initial merged config is null-prototype, but an interceptor can replace it with a normal object. If that object has no own `headers`, the read can resolve `Object.prototype.headers`. Local verification on axios `1.18.1` polluted `Object.prototype.headers = { 'X-Poisoned': 'yes' }`, installed an interceptor that returned `{ url, method, timeout, proxy: false }`, and sent a request. The loopback server received `X-Poisoned: yes`. ## Proof of Concept of Attack Constrained local demonstration: ```js Object.prototype.headers = { 'X-Poisoned': 'yes' }; const client = axios.create(); client.interceptors.request.use((config) => ({ url: config.url, method: config.method, timeout: config.timeout })); await client.get(url); ``` Expected safe behavior is that missing headers normalize to an empty header set. Current affected behavior reads inherited `Object.prototype.headers`. ## Workarounds Interceptors that rebuild config should always set an own `headers` property, for example by preserving `config.headers` or setting `headers: {}`. Mutating and returning the existing merged config also avoids replacing the null-prototype object. <details> <summary><h3>Original report</h3></summary> ## Summary Axios 1.17.0 blocks the old `Object.prototype.common` header bucket gadget. However, if a request interceptor rebuilds a minimal config object and omits `headers`, `dispatchRequest()` reads inherited `Object.prototype.headers`. This allows attacker-controlled headers to be placed on the wire. ## Affected Version Validated on: - axios: `1.17.0` - commit: `4306df2` - runtime: Node.js `v24.15.0` ## Preconditions - A separate prototype-pollution primitive can write an object to `Object.prototype.headers`. - A request interceptor rebuilds config and omits own `headers`. ## Root Cause `dispatchRequest()` uses: ```js config.headers = AxiosHeaders.from(config.headers); ``` If `config` is a normal object returned by an interceptor and lacks own `headers`, this reads `Object.prototype.headers`. ## Impact An attacker can inject request headers. Depending on the target service, this can cause cache manipulation, conditional-response suppression, request smuggling preconditions, metadata-service header injection, or application-specific authorization bypass. ## Proof of Concept ```js import axios from './index.js'; import http from 'http'; const start = (handler) => new Promise((resolve) => { const server = http.createServer(handler); server.listen(0, '127.0.0.1', () => resolve(server)); }); const stop = (server) => new Promise((resolve) => server.close(resolve)); const hits = []; const server = await start((req, res) => { hits.push(req.headers); res.setHeader('Content-Type', 'application/json'); res.end('{"ok":true}'); }); try { Object.prototype.headers = { 'X-Poisoned': 'yes', 'If-None-Match': '*' }; const client = axios.create(); client.interceptors.request.use((config) => ({ url: config.url, method: config.method, timeout: config.timeout })); await client.get(`http://127.0.0.1:${server.address().port}/headers`, { timeout: 3000 }); console.log(hits[0]); } finally { delete Object.prototype.headers; await stop(server); } ``` Observed wire headers: ```json { "x-poisoned": "yes", "if-none-match": "*", "user-agent": "axios/1.17.0" } ``` ## References - https://github.com/axios/axios/security/advisories/GHSA-898c-q2cr-xwhg - https://osv.dev/vulnerability/GHSA-898c-q2cr-xwhg </details> ---

Source published

30 Sep 2026 15:35:14 UTC

Source modified

30 Sep 2026 15:46:18 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:H/SA:N

Publisher rating · MODERATE