DescriptionA denial of service vulnerability exists in curl <v8.1.0 in the way libcurl provides several different backends for resolving host names, selected at build time. If it is built to use the synchronous resolver, it allows name resolves to time-out slow operations using `alarm()` and `siglongjmp()`. When doing this, libcurl used a global buffer that was not mutex protected and a multi-threaded application might therefore crash or otherwise misbehave.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs1036239

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
curl (PTS)buster7.64.0-4+deb10u2vulnerable
buster (security)7.64.0-4+deb10u7vulnerable
bullseye (security)7.74.0-1.3+deb11u10vulnerable
bookworm, bookworm (security)7.88.1-10+deb12u4fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs

Introduced by: (curl-7_9_8)
Fixed by: (curl-8_1_0)
Follow-up: (curl-8_1_0)
Debian binary package builds are not affected as the "curl_jmpenv" variable declaration was guarded
by a "#ifdef HAVE_SIGSETJMP", but the variable would only be used on "#ifdef USE_ALARM_TIMEOUT". For
Debian, "HAVE_SIGSETJMP" is true but "USE_ALARM_TIMEOUT" is false, and the threaded resolver is used.

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