Coder: Workspace agent API insecure redirect handling allowed cross-agent file read and write

Description

Coder allows organizations to provision remote development environments via Terraform. Prior to 2.29.19, 2.32.9, 2.33.10, and 2.34.4, agentConn.apiClient() follows redirects while its custom transport accepts the host from the redirected request URL when the port is the workspace agent HTTP API port 4. An authenticated user who controls a modified workspace agent and knows another online agent's UUID can derive the victim's tailnet address and redirect control-plane requests to that agent. HTTP 301, 302, and 303 redirects can redirect read requests, while HTTP 307 and 308 preserve replayable write and process-start requests. The redirected workspace agent file APIs can read or write files as the victim workspace user, and affected versions exposing the workspace agent process API can execute commands after a redirected file write, crossing workspace and tenant boundaries. This issue is fixed in versions 2.29.19, 2.32.9, 2.33.10, and 2.34.4.

Scores

EPSS (exploitation in 30 days)

0.76% · top 44% of all CVEs (6 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: no · Technical impact: total

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.3.

Weakness

• CWE-863: Incorrect Authorization (opens in a new tab)All about CWE-863 and its CVEs
• CWE-918: Server-Side Request Forgery (SSRF) (opens in a new tab)All about CWE-918 and its CVEs

Affected products

• coder · coder

  • affected >= 2.27.0, < 2.29.19
  • affected >= 2.30.0, < 2.32.9
  • affected >= 2.33.0, < 2.33.10
  • affected >= 2.34.0, < 2.34.4

References (15)

• https://github.com/coder/coder/security/advisories/GHSA-qrwj-vh9x-gw5v (opens in a new tab)x_refsource_CONFIRM
• https://github.com/coder/coder/pull/26600 (opens in a new tab)x_refsource_MISC
• https://github.com/coder/coder/pull/26611 (opens in a new tab)x_refsource_MISC
• https://github.com/coder/coder/pull/26612 (opens in a new tab)x_refsource_MISC
• https://github.com/coder/coder/pull/26613 (opens in a new tab)x_refsource_MISC
• https://github.com/coder/coder/pull/26622 (opens in a new tab)x_refsource_MISC
• https://github.com/coder/coder/commit/2312b67bc52c4e314c18c4b4be5dcf5500c94ad7 (opens in a new tab)x_refsource_MISC
• https://github.com/coder/coder/commit/812549d671d0f5a0b45adcee860d37b70aaddccd (opens in a new tab)x_refsource_MISC
• https://github.com/coder/coder/commit/ec3ba84c0002f47dd979c073cde1ab345acbaea5 (opens in a new tab)x_refsource_MISC
• https://github.com/coder/coder/commit/eeb2624549ddb85538e493af3e678fdb185a809f (opens in a new tab)x_refsource_MISC
• https://github.com/coder/coder/commit/f8bdec5add4711650d5bfb6ff93d0cc9d7821c81 (opens in a new tab)x_refsource_MISC
• https://github.com/coder/coder/releases/tag/v2.29.19 (opens in a new tab)x_refsource_MISC
• https://github.com/coder/coder/releases/tag/v2.32.9 (opens in a new tab)x_refsource_MISC
• https://github.com/coder/coder/releases/tag/v2.33.10 (opens in a new tab)x_refsource_MISC
• https://github.com/coder/coder/releases/tag/v2.34.4 (opens in a new tab)x_refsource_MISC

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-63443](https://trackcve.app/badge/CVE-2026-63443.svg)](https://trackcve.app/cve/CVE-2026-63443)

Record last updated 15 Sept 2026, 17:31 UTC.