CVE-2026-55078: Coder · Zip upload decompression lacks aggregate size limit, enabling denial of service
Affects github.com/coder/coder/v2Source GCVE Database
Not known to be exploited · CVSS 6.5 Medium : upgrade to 2.34.2 when convenient.
Data as of 29 Oct 2026, 19:04 UTC
- EPSS
- 0.6% chance of exploitation in 30 days – higher than 48% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 2.34.2, 2.33.8, 2.32.7 +1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 6 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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 29 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Gogithub.com/coder/coder/v2 | Affected
| Fixed in
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| Gogithub.com/coder/coder/v2 | Affected
| Fixed in
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| Gogithub.com/coder/coder/v2 | Affected
| Fixed in
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| Gogithub.com/coder/coder/v2 | Affected
| Fixed in
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Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Apply the official patches available in versions v2.34.2, v2.33.8, v2.32.7, and v2.29.17 or later. Until patched, restrict file-upload permissions to trusted users only or deploy a reverse proxy with request-body size limits in front of coderd to limit upload sizes. The vendor has provided official fixes for all supported release lines.
Description
### Summary `POST /api/v2/files` converts zip uploads to tar in memory via `CreateTarFromZip`, which enforced a per-entry size limit but no aggregate limit on total decompressed output, writing to an unbounded in-memory buffer. > **Note:** Exploitation requires authenticated file-upload access and the impact is limited to availability (denial of service). ### Impact An authenticated user could upload a zip within the 100 MiB upload limit but containing many highly compressible entries whose decompressed size exhausted memory, crashing `coderd` before any RBAC check. Repeated requests could keep the service unavailable. This is a denial of service; it does not allow data disclosure or code execution. ### Patches The fix adds a metadata preflight check that sums projected entry sizes and a streaming writer that enforces the aggregate limit during decompression. The fix was backported to all supported release lines: | Release line | Patched version | |---|---| | 2.34 | [v2.34.2](https://github.com/coder/coder/releases/tag/v2.34.2) | | 2.33 | [v2.33.8](https://github.com/coder/coder/releases/tag/v2.33.8) | | 2.32 | [v2.32.7](https://github.com/coder/coder/releases/tag/v2.32.7) | | 2.29 (ESR) | [v2.29.17](https://github.com/coder/coder/releases/tag/v2.29.17) | ### Workarounds Restrict file-upload permissions to trusted users or place a reverse proxy with request-body size limits in front of `coderd`. ### Resources - Fix: #25877 ### Credits Coder would like to thank Anthropic's Security Team (ANT-2026-22438) for independently disclosing this issue!