Out-of-bounds Write Affecting capnproto package, versions <1.0.1-3


Severity

Recommended
0.0
critical
0
10

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Threat Intelligence

EPSS
0.81% (82nd percentile)

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  • Snyk IDSNYK-DEBIANUNSTABLE-CAPNPROTO-6071668
  • published22 Nov 2023
  • disclosed21 Nov 2023

Introduced: 21 Nov 2023

CVE-2023-48230  (opens in a new tab)
CWE-787  (opens in a new tab)

How to fix?

Upgrade Debian:unstable capnproto to version 1.0.1-3 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream capnproto package and not the capnproto package as distributed by Debian. See How to fix? for Debian:unstable relevant fixed versions and status.

Cap'n Proto is a data interchange format and capability-based RPC system. In versions 1.0 and 1.0.1, when using the KJ HTTP library with WebSocket compression enabled, a buffer underrun can be caused by a remote peer. The underrun always writes a constant value that is not attacker-controlled, likely resulting in a crash, enabling a remote denial-of-service attack. Most Cap'n Proto and KJ users are unlikely to have this functionality enabled and so unlikely to be affected. Maintainers suspect only the Cloudflare Workers Runtime is affected.

If KJ HTTP is used with WebSocket compression enabled, a malicious peer may be able to cause a buffer underrun on a heap-allocated buffer. KJ HTTP is an optional library bundled with Cap'n Proto, but is not directly used by Cap'n Proto. WebSocket compression is disabled by default. It must be enabled via a setting passed to the KJ HTTP library via HttpClientSettings or HttpServerSettings. The bytes written out-of-bounds are always a specific constant 4-byte string { 0x00, 0x00, 0xFF, 0xFF }. Because this string is not controlled by the attacker, maintainers believe it is unlikely that remote code execution is possible. However, it cannot be ruled out. This functionality first appeared in Cap'n Proto 1.0. Previous versions are not affected.

This issue is fixed in Cap'n Proto 1.0.1.1.

CVSS Scores

version 3.1