Name | CVE-2024-5535 |
Description | Issue summary: Calling the OpenSSL API function SSL_select_next_proto with an
empty supported client protocols buffer may cause a crash or memory contents to
be sent to the peer.
Impact summary: A buffer overread can have a range of potential consequences
such as unexpected application beahviour or a crash. In particular this issue
could result in up to 255 bytes of arbitrary private data from memory being sent
to the peer leading to a loss of confidentiality. However, only applications
that directly call the SSL_select_next_proto function with a 0 length list of
supported client protocols are affected by this issue. This would normally never
be a valid scenario and is typically not under attacker control but may occur by
accident in the case of a configuration or programming error in the calling
application.
The OpenSSL API function SSL_select_next_proto is typically used by TLS
applications that support ALPN (Application Layer Protocol Negotiation) or NPN
(Next Protocol Negotiation). NPN is older, was never standardised and
is deprecated in favour of ALPN. We believe that ALPN is significantly more
widely deployed than NPN. The SSL_select_next_proto function accepts a list of
protocols from the server and a list of protocols from the client and returns
the first protocol that appears in the server list that also appears in the
client list. In the case of no overlap between the two lists it returns the
first item in the client list. In either case it will signal whether an overlap
between the two lists was found. In the case where SSL_select_next_proto is
called with a zero length client list it fails to notice this condition and
returns the memory immediately following the client list pointer (and reports
that there was no overlap in the lists).
This function is typically called from a server side application callback for
ALPN or a client side application callback for NPN. In the case of ALPN the list
of protocols supplied by the client is guaranteed by libssl to never be zero in
length. The list of server protocols comes from the application and should never
normally be expected to be of zero length. In this case if the
SSL_select_next_proto function has been called as expected (with the list
supplied by the client passed in the client/client_len parameters), then the
application will not be vulnerable to this issue. If the application has
accidentally been configured with a zero length server list, and has
accidentally passed that zero length server list in the client/client_len
parameters, and has additionally failed to correctly handle a "no overlap"
response (which would normally result in a handshake failure in ALPN) then it
will be vulnerable to this problem.
In the case of NPN, the protocol permits the client to opportunistically select
a protocol when there is no overlap. OpenSSL returns the first client protocol
in the no overlap case in support of this. The list of client protocols comes
from the application and should never normally be expected to be of zero length.
However if the SSL_select_next_proto function is accidentally called with a
client_len of 0 then an invalid memory pointer will be returned instead. If the
application uses this output as the opportunistic protocol then the loss of
confidentiality will occur.
This issue has been assessed as Low severity because applications are most
likely to be vulnerable if they are using NPN instead of ALPN - but NPN is not
widely used. It also requires an application configuration or programming error.
Finally, this issue would not typically be under attacker control making active
exploitation unlikely.
The FIPS modules in 3.3, 3.2, 3.1 and 3.0 are not affected by this issue.
Due to the low severity of this issue we are not issuing new releases of
OpenSSL at this time. The fix will be included in the next releases when they
become available. |
Source | CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
Debian Bugs | 1074487 |
Vulnerable and fixed packages
The table below lists information on source packages.
Source Package | Release | Version | Status |
---|
openssl (PTS) | jessie, jessie (lts) | 1.0.1t-1+deb8u21 | vulnerable |
| stretch (security) | 1.1.0l-1~deb9u6 | vulnerable |
| stretch (lts), stretch | 1.1.0l-1~deb9u9 | vulnerable |
| buster (security), buster, buster (lts) | 1.1.1n-0+deb10u6 | vulnerable |
| bullseye | 1.1.1w-0+deb11u1 | vulnerable |
| bullseye (security) | 1.1.1n-0+deb11u5 | vulnerable |
| bookworm | 3.0.14-1~deb12u1 | vulnerable |
| bookworm (security) | 3.0.14-1~deb12u2 | vulnerable |
| trixie | 3.3.1-7 | vulnerable |
| sid | 3.3.2-1 | fixed |
openssl1.0 (PTS) | stretch (security) | 1.0.2u-1~deb9u7 | vulnerable |
| stretch (lts), stretch | 1.0.2u-1~deb9u9 | vulnerable |
The information below is based on the following data on fixed versions.
Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
---|
openssl | source | (unstable) | 3.3.2-1 | | | 1074487 |
openssl1.0 | source | (unstable) | (unfixed) | | | |
Notes
[bookworm] - openssl <postponed> (Minor issue, fix along with next update round)
[bullseye] - openssl <postponed> (Minor issue, fix along with next update round)
https://www.openssl.org/news/secadv/20240627.txt
https://github.com/openssl/openssl/commit/2ebbe2d7ca8551c4cb5fbb391ab9af411708090e
https://github.com/openssl/openssl/commit/c6e1ea223510bb7104bf0c41c0c45eda5a16b718
https://github.com/openssl/openssl/commit/fc8ff75814767d6c55ea78d05adc72cd346d0f0a
https://github.com/openssl/openssl/commit/a210f580f450bbd08fac85f06e27107b8c580f9b
https://github.com/openssl/openssl/commit/0d883f6309b6905d29ffded6d703ded39385579c
https://github.com/openssl/openssl/commit/9925c97a8e8c9887765a0979c35b516bc8c3af85
https://github.com/openssl/openssl/commit/e10a3a84bf73a3e6024c338b51f2fb4e78a3dee9
https://github.com/openssl/openssl/commit/238fa464d6e38aa2c92af70ef9580c74cff512e4
https://github.com/openssl/openssl/commit/de71058567b84c6e14b758a383e1862eb3efb921
https://github.com/openssl/openssl/commit/214c724e00d594c3eecf4b740ee7af772f0ee04a
[buster] - openssl <postponed> (Minor issue, fix along with next update round)
[stretch] - openssl <postponed> (Minor issue, fix along with next update round)
[jessie] - openssl <postponed> (Minor issue, fix along with next update round)
[stretch] - openssl1.0 <postponed> (Minor issue, fix along with next update round)