CVE-2021-22947

NameCVE-2021-22947
DescriptionWhen curl >= 7.20.0 and <= 7.78.0 connects to an IMAP or POP3 server to retrieve data using STARTTLS to upgrade to TLS security, the server can respond and send back multiple responses at once that curl caches. curl would then upgrade to TLS but not flush the in-queue of cached responses but instead continue using and trustingthe responses it got *before* the TLS handshake as if they were authenticated.Using this flaw, it allows a Man-In-The-Middle attacker to first inject the fake responses, then pass-through the TLS traffic from the legitimate server and trick curl into sending data back to the user thinking the attacker's injected data comes from the TLS-protected server.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub advisories/code/issues, web search, more)
ReferencesDLA-2773-1, DLA-3085-1, DSA-5197-1

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+deb10u3fixed
bullseye7.74.0-1.3+deb11u3fixed
bullseye (security)7.74.0-1.3+deb11u2fixed
bookworm, sid7.86.0-2fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
curlsourcestretch7.52.1-5+deb9u16DLA-2773-1
curlsourcebuster7.64.0-4+deb10u3DLA-3085-1
curlsourcebullseye7.74.0-1.3+deb11u2DSA-5197-1
curlsource(unstable)7.79.1-1

Notes

https://curl.se/docs/CVE-2021-22947.html
Fixed by: https://github.com/curl/curl/commit/8ef147c43646e91fdaad5d0e7b60351f842e5c68 (curl-7_79_0)

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