faktory: Uncaught Exception
CVE-2026-63403 is a high-severity uncaught exception vulnerability in faktory from Contribsys, with a CVSS 4.0 base score of 8.7 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected faktory versions: < 1.10.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.45% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of faktory you run against the affected versions below, and install the vendor's latest release.
- 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.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Contribsys | faktory | < 1.10.0 | Not stated |
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.
- Attack requirements
- NoneThe attack does not depend on a particular deployment or configuration.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Confidentiality (vulnerable system)
- NoneNo loss of confidentiality on the vulnerable system.
- Integrity (vulnerable system)
- NoneNo loss of integrity on the vulnerable system.
- Availability (vulnerable system)
- HighSerious loss of availability on the vulnerable system.
- Confidentiality (other systems)
- NoneNo loss of confidentiality on systems beyond the vulnerable one.
- Integrity (other systems)
- NoneNo loss of integrity on systems beyond the vulnerable one.
- Availability (other systems)
- NoneNo loss of availability on systems beyond the vulnerable one.
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/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. Scored by CNA (github.com).
Official description
Faktory is a language-agnostic background job server. In versions prior to 1.10.0, the server is vulnerable to an unauthenticated denial of service in which a single malformed command crashes the entire process. Its wire protocol is line-based, and several command handlers slice or index the received line at a fixed offset, such as cmd[5:] for PUSH or qs[0] for QUEUE, without checking that a payload is present. Sending a bare verb with no payload, for example PUSH, ACK, FAIL, BEAT, PUSHB, or QUEUE, triggers a Go slice or index out-of-range panic. Because the codebase has no recover() anywhere in the command-dispatch path, an unrecovered panic in a handler goroutine terminates the whole Go process rather than just that connection, instantly disconnecting every other client, worker, and in-flight job. The attack requires only a connection to the command port and completion of the trivial handshake, with no credentials when no password is configured, and can be repeated to keep the service down indefinitely. This issue is fixed in version 1.10.0.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Uncaught Exception
An exception is thrown from a function, but it is not caught.
How developers prevent this class of flaw
- The choice between a language which has named or unnamed exceptions needs to be done. While unnamed exceptions exacerbate the chance of not properly dealing with an exception, named exceptions suffer from the up call version of the weak base class problem.
- A language can be used which requires, at compile time, to catch all serious exceptions. However, one must make sure to use the most current version of the API as new exceptions could be added.
- Catch all relevant exceptions. This is the recommended solution. Ensure that all exceptions are handled in such a way that you can be sure of the state of your system at any given moment.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other vulnerabilities in faktory
- 7.3 High severity
- 7.5 High severity
Recent Uncaught Exception vulnerabilities
- 8.7 High severity
- 8.9 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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