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CVE-2019-11841

Published: 22 May 2019

A message-forgery issue was discovered in crypto/openpgp/clearsign/clearsign.go in supplementary Go cryptography libraries 2019-03-25. According to the OpenPGP Message Format specification in RFC 4880 chapter 7, a cleartext signed message can contain one or more optional "Hash" Armor Headers. The "Hash" Armor Header specifies the message digest algorithm(s) used for the signature. However, the Go clearsign package ignores the value of this header, which allows an attacker to spoof it. Consequently, an attacker can lead a victim to believe the signature was generated using a different message digest algorithm than what was actually used. Moreover, since the library skips Armor Header parsing in general, an attacker can not only embed arbitrary Armor Headers, but also prepend arbitrary text to cleartext messages without invalidating the signatures.

Notes

AuthorNote
jdstrand
snapd contains an embedded copy of golang-go.crypto
the version of golang-go.crypto that is embedded does not contain
the clearsign package. Nothing in the source uses the clearsign APIs

Priority

Medium

Cvss 3 Severity Score

5.9

Score breakdown

Status

Package Release Status
golang-go.crypto
Launchpad, Ubuntu, Debian
focal Not vulnerable
(1:0.0~git20200221.2aa609c-1)
hirsute Not vulnerable
(1:0.0~git20200221.2aa609c-1)
bionic Needed

cosmic Ignored
(end of life)
disco Ignored
(end of life)
eoan Ignored
(end of life)
groovy Not vulnerable
(1:0.0~git20200221.2aa609c-1)
impish Not vulnerable
(1:0.0~git20200221.2aa609c-1)
jammy Not vulnerable
(1:0.0~git20200221.2aa609c-1)
kinetic Not vulnerable
(1:0.0~git20200221.2aa609c-1)
lunar Not vulnerable
(1:0.0~git20200221.2aa609c-1)
upstream Needs triage

xenial Needed

mantic Not vulnerable
(1:0.0~git20200221.2aa609c-1)
Patches:
upstream: https://go.googlesource.com/crypto/+/c05e17bb3b2dca130fc919668a96b4bec9eb9442
snapd
Launchpad, Ubuntu, Debian
bionic Not vulnerable
(code-not-present)
focal Not vulnerable
(code-not-present)
upstream Not vulnerable
(code-not-present)
hirsute Not vulnerable
(code-not-present)
cosmic Not vulnerable
(code-not-present)
disco Not vulnerable
(code-not-present)
eoan Not vulnerable
(code-not-present)
groovy Not vulnerable
(code-not-present)
impish Not vulnerable
(code-not-present)
jammy Not vulnerable
(code-not-present)
kinetic Not vulnerable
(code-not-present)
lunar Not vulnerable
(code-not-present)
xenial Not vulnerable
(code-not-present)
mantic Not vulnerable
(code-not-present)

Severity score breakdown

Parameter Value
Base score 5.9
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact High
Availability impact None
Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N