DeerFlow: Incomplete List of Disallowed Inputs
CVE-2026-34430 is a critical-severity incomplete list of disallowed inputs vulnerability in DeerFlow from ByteDance, with a CVSS 3.1 base score of 9.6 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists version 92c7a20cb74addc3038d2131da78f2e239ef542e as the first without the flaw, so updating DeerFlow to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.41% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update DeerFlow to 92c7a20cb74addc3038d2131da78f2e239ef542e or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Bytedance | DeerFlow | before 92c7a20cb74addc3038d2131da78f2e239ef542e | 92c7a20cb74addc3038d2131da78f2e239ef542e |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.6 | High | CNA (vulncheck.com) |
| CVSS 3.1 | 8.8 | High | CNA (vulncheck.com) |
| CVSS 3.1 | 9.6 | Critical | NVD |
Official description
ByteDance DeerFlow versions prior to commit 92c7a20 contain a sandbox escape vulnerability in bash tool handling that allows attackers to execute arbitrary commands on the host system by bypassing regex-based validation using shell features such as directory changes and relative paths. Attackers can exploit the incomplete shell semantics modeling to read and modify files outside the sandbox boundary and achieve arbitrary command execution through subprocess invocation with shell interpretation enabled.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Incomplete List of Disallowed Inputs
The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are not allowed by policy or otherwise require other action to neutralize before additional processing takes place, but the list is incomplete.
How developers prevent this class of flaw
- Do not rely exclusively on detecting disallowed inputs. There are too many variants to encode a character, especially when different environments are used, so there is a high likelihood of missing some variants. Only use detection of disallowed inputs as a mechanism for detecting suspicious activity. Ensure that you are using other protection mechanisms that only identify good input - such as lists of allowed inputs - and ensure that you are properly encoding your outputs.
More Incomplete List of Disallowed Inputs vulnerabilities (CWE-184)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- github.com/bytedance/deer-flow/pull/1547Issue Tracking
Patches and release notes
Third-party and government advisories
- vulncheck.com/advisories/bytedance-deerflow-localsandboxprovider-host-bash-escapeThird Party Advisory, VDB Entry
Other vulnerabilities in DeerFlow
- 9.1 Critical severity
Recent Incomplete List of Disallowed Inputs vulnerabilities
- 7.8 High severity
- 8.8 High severity
- 7.1 High severity
- 8.8 High severity
- 7.5 High severity
- 7.8 High severity
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