SwiftNIO HTTP2: Integer Overflow or Wraparound
CVE-2022-24667 is a high-severity integer overflow or wraparound vulnerability in SwiftNIO HTTP2 from Swift Project, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected SwiftNIO HTTP2 versions: 1.0.0; 1.19.1 and earlier. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.12% chance of exploitation within 30 days, higher than 67% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Swiftnio Http/2 to 1.19.2 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 |
|---|---|---|---|
| Swift Project | SwiftNIO HTTP2 | 1.0.0; 1.19.1 and earlier | Not stated |
| Apple | Swiftnio Http/2 | 1.0.0 up to, but not including, 1.19.2 | 1.19.2 |
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
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.5 | High | NVD |
| CVSS 2.0 | 5.0 | Medium | NVD |
Official description
A program using swift-nio-http2 is vulnerable to a denial of service attack, caused by a network peer sending a specially crafted HPACK-encoded header block. This attack affects all swift-nio-http2 versions from 1.0.0 to 1.19.1. There are a number of implementation errors in the parsing of HPACK-encoded header blocks that allow maliciously crafted HPACK header blocks to cause crashes in processes using swift-nio-http2. Each of these crashes is triggered instead of an integer overflow. A malicious HPACK header block could be sent on any of the HPACK-carrying frames in a HTTP/2 connection (HEADERS and PUSH_PROMISE), at any position. Sending a HPACK header block does not require any special permission, so any HTTP/2 connection peer may send one. For clients, this means any server to which they connect may launch this attack. For servers, anyone they allow to connect to them may launch such an attack. The attack is low-effort: it takes very little resources to send an appropriately crafted field block. The impact on availability is high: receiving a frame carrying this field block immediately crashes the server, dropping all in-flight connections and causing the service to need to restart. It is straightforward for an attacker to repeatedly send appropriately crafted field blocks, so attackers require very few resources to achieve a substantial denial of service. The attack does not have any confidentiality or integrity risks in and of itself: swift-nio-http2 is parsing the field block in memory-safe code and the crash is triggered instead of an integer overflow. However, sudden process crashes can lead to violations of invariants in services, so it is possible that this attack can be used to trigger an error condition that has confidentiality or integrity risks. The risk can be mitigated if untrusted peers can be prevented from communicating with the service. This mitigation is not available to many services. The issue is fixed by rewriting the parsing code to correctly handle all conditions in the function. The principal issue was found by automated fuzzing by oss-fuzz, but several associated bugs in the same code were found by code audit and fixed at the same time
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Integer Overflow or Wraparound
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
How developers prevent this class of flaw
- Ensure that all protocols are strictly defined, such that all out-of-bounds behavior can be identified simply, and require strict conformance to the protocol.
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. If possible, choose a language or compiler that performs automatic bounds checking.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Use libraries or frameworks that make it easier to handle numbers without unexpected consequences. Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++).
More Integer Overflow or Wraparound vulnerabilities (CWE-190)
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Advisories
- github.com/apple/swift-nio-http2/security/advisories/GHSA-w3f6-pc54-gfw7Third Party Advisory
Other vulnerabilities in SwiftNIO HTTP2
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
Recent Integer Overflow or Wraparound vulnerabilities
- 9.8 Critical severity
- 9.8 Critical severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
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