sofa-rpc: Improper Neutralization of Special Elements used in an Expression Language Statement
CVE-2023-41331 is a critical-severity improper neutralization of special elements used in an expression language statement vulnerability in sofa-rpc from Sofastack, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected sofa-rpc versions: < 5.11.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.64% chance of exploitation within 30 days, higher than 77% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Sofarpc to 5.11.0 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.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Sofastack | sofa-rpc | < 5.11.0 | Not stated |
| Sofastack | Sofarpc | before 5.11.0 | 5.11.0 |
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
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- 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:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 9.8 | Critical | CNA (github.com) |
| CVSS 3.1 | 9.8 | Critical | NVD |
Official description
SOFARPC is a Java RPC framework. Versions prior to 5.11.0 are vulnerable to remote command execution. Through a carefully crafted payload, an attacker can achieve JNDI injection or system command execution. In the default configuration of the SOFARPC framework, a blacklist is used to filter out dangerous classes encountered during the deserialization process. However, the blacklist is not comprehensive, and an actor can exploit certain native JDK classes and common third-party packages to construct gadget chains capable of achieving JNDI injection or system command execution attacks. Version 5.11.0 contains a fix for this issue. As a workaround, users can add `-Drpc_serialize_blacklist_override=javax.sound.sampled.AudioFileFormat` to the blacklist.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Neutralization of Special Elements used in an Expression Language Statement
The product constructs all or part of an expression language (EL) statement in a framework such as a Java Server Page (JSP) using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended EL statement before it is executed.
How developers prevent this class of flaw
- Avoid adding user-controlled data into an expression interpreter when possible.
- If user-controlled data must be added to an expression interpreter, one or more of the following should be performed: Validate that the user input will not evaluate as an expression Encode the user input in a way that ensures it is not evaluated as an expression
- The framework or tooling might allow the developer to disable or deactivate the processing of EL expressions, such as setting the isELIgnored attribute for a JSP page to true.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Patches and release notes
- github.com/sofastack/sofa-rpc/releases/tag/v5.11.0Release Notes
Other vulnerabilities in sofa-rpc
- 9.8 Critical severity
Recent Improper Neutralization of Special Elements used in an Expression Language Statement vulnerabilities
- 9.8 Critical severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 9.8 Critical severity
- 9.8 Critical severity
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