CVE-2021-23993
published 2021-06-24CVE-2021-23993: An attacker may perform a DoS attack to prevent a user from sending encrypted email to a correspondent. If an attacker creates a crafted OpenPGP key with a…
PriorityP430medium6.5CVSS 3.1
AVNACLPRNUIRSUCNIHAN
EPSS
0.43%
35.0th percentile
An attacker may perform a DoS attack to prevent a user from sending encrypted email to a correspondent. If an attacker creates a crafted OpenPGP key with a subkey that has an invalid self signature, and the Thunderbird user imports the crafted key, then Thunderbird may try to use the invalid subkey, but the RNP library rejects it from being used, causing encryption to fail. This vulnerability affects Thunderbird < 78.9.1.
Affected
10 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | thunderbird | < thunderbird 1:78.10.0-1 (bookworm) | thunderbird 1:78.10.0-1 (bookworm) |
| mozilla | firefox | — | — |
| mozilla | thunderbird | < 78.9.1 | 78.9.1 |
| mozilla | thunderbird | >= 0 < 1:78.10.0-1 | 1:78.10.0-1 |
| mozilla | thunderbird | >= 0 < 1:78.10.0-1 | 1:78.10.0-1 |
| mozilla | thunderbird | >= 0 < 1:78.10.0-1 | 1:78.10.0-1 |
| mozilla | thunderbird | >= 0 < 1:78.10.0-1 | 1:78.10.0-1 |
| mozilla | thunderbird | >= 0 < 1:78.11.0+build1-0ubuntu0.18.04.2 | 1:78.11.0+build1-0ubuntu0.18.04.2 |
| mozilla | thunderbird | >= 0 < 1:78.11.0+build1-0ubuntu0.20.04.2 | 1:78.11.0+build1-0ubuntu0.20.04.2 |
| mozilla | thunderbird | >= unspecified < 78.9.1 | 78.9.1 |
CVSS provenance
nvdv3.16.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
nvdv2.04.3MEDIUMAV:N/AC:M/Au:N/C:N/I:P/A:N
osv7.4HIGH
vendor_ubuntu7.4HIGH
vendor_debian6.5MEDIUM
vendor_redhat6.5MEDIUM
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Ubuntu
Thunderbird vulnerabilities
vendor_ubuntu·2021-06-25·CVSS 7.4
CVE-2021-29948 [HIGH] Thunderbird vulnerabilities
Title: Thunderbird vulnerabilities
Summary: Several security issues were fixed in Thunderbird.
USN-4995-1 fixed vulnerabilities in Thunderbird. This update provides
the corresponding updates for Ubuntu 18.04 LTS.
Original advisory details:
Multiple security issues were discovered in Thunderbird. If a user were
tricked into opening a specially crafted website in a browsing context, an
attacker could potentially exploit these to cause a denial of service,
obtain sensitive information, spoof the UI, bypass security restrictions,
or execute arbitrary code. (CVE-2021-23961, CVE-2021-23981,
CVE-2021-23982, CVE-2021-23987, CVE-2021-23994, CVE-2021-23998,
CVE-2021-23999, CVE-2021-29945, CVE-2021-29946, CVE-2021-29967)
It was discovered that extensions could open popup windows with control
of
Ubuntu
Thunderbird vulnerabilities
vendor_ubuntu·2021-06-22·CVSS 7.4
CVE-2021-23961 [HIGH] Thunderbird vulnerabilities
Title: Thunderbird vulnerabilities
Summary: Several security issues were fixed in Thunderbird.
Multiple security issues were discovered in Thunderbird. If a user were
tricked into opening a specially crafted website in a browsing context, an
attacker could potentially exploit these to cause a denial of service,
obtain sensitive information, spoof the UI, bypass security restrictions,
or execute arbitrary code. (CVE-2021-23961, CVE-2021-23981,
CVE-2021-23982, CVE-2021-23987, CVE-2021-23994, CVE-2021-23998,
CVE-2021-23999, CVE-2021-29945, CVE-2021-29946, CVE-2021-29967)
It was discovered that extensions could open popup windows with control
of the window title in some circumstances. If a user were tricked into
installing a specially crafted extension, an attacker could potentially
exploit
Red Hat
Mozilla: Inability to send encrypted OpenPGP email after importing a crafted OpenPGP key
vendor_redhat·2021-04-08·CVSS 6.5
CVE-2021-23993 [MEDIUM] CWE-347 Mozilla: Inability to send encrypted OpenPGP email after importing a crafted OpenPGP key
Mozilla: Inability to send encrypted OpenPGP email after importing a crafted OpenPGP key
An attacker may perform a DoS attack to prevent a user from sending encrypted email to a correspondent. If an attacker creates a crafted OpenPGP key with a subkey that has an invalid self signature, and the Thunderbird user imports the crafted key, then Thunderbird may try to use the invalid subkey, but the RNP library rejects it from being used, causing encryption to fail. This vulnerability affects Thunderbird < 78.9.1.
Package: thunderbird (Red Hat Enterprise Linux 6) - Out of support scope
Debian
CVE-2021-23993: thunderbird - An attacker may perform a DoS attack to prevent a user from sending encrypted em...
vendor_debian·2021·CVSS 6.5
CVE-2021-23993 [MEDIUM] CVE-2021-23993: thunderbird - An attacker may perform a DoS attack to prevent a user from sending encrypted em...
An attacker may perform a DoS attack to prevent a user from sending encrypted email to a correspondent. If an attacker creates a crafted OpenPGP key with a subkey that has an invalid self signature, and the Thunderbird user imports the crafted key, then Thunderbird may try to use the invalid subkey, but the RNP library rejects it from being used, causing encryption to fail. This vulnerability affects Thunderbird < 78.9.1.
Scope: local
bookworm: resolved (fixed in 1:78.10.0-1)
bullseye: resolved (fixed in 1:78.10.0-1)
forky: resolved (fixed in 1:78.10.0-1)
sid: resolved (fixed in 1:78.10.0-1)
trixie: resolved (fixed in 1:78.10.0-1)
Mozilla
Mozilla Foundation Security Advisory 2021-13: CVE-2021-23993
vendor_mozilla·CVSS 6.5
CVE-2021-23993 [MEDIUM] Mozilla Foundation Security Advisory 2021-13: CVE-2021-23993
Mozilla Foundation Security Advisory 2021-13
CVE: CVE-2021-23993
Product: Thunderbird
Impact: low
Fixed in: Thunderbird 78.9.1
GHSA
MailKit has STARTTLS Response Injection via unflushed stream buffer that enables SASL mechanism downgrade
ghsa·2026-04-18
CVE-2021-23993 [MEDIUM] CWE-74 MailKit has STARTTLS Response Injection via unflushed stream buffer that enables SASL mechanism downgrade
MailKit has STARTTLS Response Injection via unflushed stream buffer that enables SASL mechanism downgrade
### Summary
A STARTTLS Response Injection vulnerability in MailKit allows a Man-in-the-Middle attacker to inject arbitrary protocol responses across the plaintext-to-TLS trust boundary, enabling SASL authentication mechanism downgrade (e.g., forcing PLAIN instead of SCRAM-SHA-256). The internal read buffer in `SmtpStream`, `ImapStream`, and `Pop3Stream` is not flushed when the underlying stream is replaced with `SslStream` during STARTTLS upgrade, causing pre-TLS attacker-injected data to be processed as trusted post-TLS responses. This is the same vulnerability class as CVE-2021-23993 (Thunderbird), CVE-2021-33515 (Dovecot), and CVE-2011-0411 (Postfix).
### Details
The `Stream` pr
GHSA
GHSA-3pj2-rvj5-6646: An attacker may perform a DoS attack to prevent a user from sending encrypted email to a correspondent
ghsa_unreviewed·2022-05-24
CVE-2021-23993 [MEDIUM] CWE-327 GHSA-3pj2-rvj5-6646: An attacker may perform a DoS attack to prevent a user from sending encrypted email to a correspondent
An attacker may perform a DoS attack to prevent a user from sending encrypted email to a correspondent. If an attacker creates a crafted OpenPGP key with a subkey that has an invalid self signature, and the Thunderbird user imports the crafted key, then Thunderbird may try to use the invalid subkey, but the RNP library rejects it from being used, causing encryption to fail. This vulnerability affects Thunderbird < 78.9.1.
OSV
thunderbird vulnerabilities
osv·2021-06-25·CVSS 7.4
[HIGH] thunderbird vulnerabilities
thunderbird vulnerabilities
USN-4995-1 fixed vulnerabilities in Thunderbird. This update provides
the corresponding updates for Ubuntu 18.04 LTS.
Original advisory details:
Multiple security issues were discovered in Thunderbird. If a user were
tricked into opening a specially crafted website in a browsing context, an
attacker could potentially exploit these to cause a denial of service,
obtain sensitive information, spoof the UI, bypass security restrictions,
or execute arbitrary code. (CVE-2021-23961, CVE-2021-23981,
CVE-2021-23982, CVE-2021-23987, CVE-2021-23994, CVE-2021-23998,
CVE-2021-23999, CVE-2021-29945, CVE-2021-29946, CVE-2021-29967)
It was discovered that extensions could open popup windows with control
of the window title in some circumstances. If a user were tricked into
OSV
CVE-2021-23993: An attacker may perform a DoS attack to prevent a user from sending encrypted email to a correspondent
osv·2021-06-24·CVSS 6.5
CVE-2021-23993 [MEDIUM] CVE-2021-23993: An attacker may perform a DoS attack to prevent a user from sending encrypted email to a correspondent
An attacker may perform a DoS attack to prevent a user from sending encrypted email to a correspondent. If an attacker creates a crafted OpenPGP key with a subkey that has an invalid self signature, and the Thunderbird user imports the crafted key, then Thunderbird may try to use the invalid subkey, but the RNP library rejects it from being used, causing encryption to fail. This vulnerability affects Thunderbird < 78.9.1.
OSV
thunderbird vulnerabilities
osv·2021-06-22·CVSS 7.4
CVE-2021-23961 [HIGH] thunderbird vulnerabilities
thunderbird vulnerabilities
Multiple security issues were discovered in Thunderbird. If a user were
tricked into opening a specially crafted website in a browsing context, an
attacker could potentially exploit these to cause a denial of service,
obtain sensitive information, spoof the UI, bypass security restrictions,
or execute arbitrary code. (CVE-2021-23961, CVE-2021-23981,
CVE-2021-23982, CVE-2021-23987, CVE-2021-23994, CVE-2021-23998,
CVE-2021-23999, CVE-2021-29945, CVE-2021-29946, CVE-2021-29967)
It was discovered that extensions could open popup windows with control
of the window title in some circumstances. If a user were tricked into
installing a specially crafted extension, an attacker could potentially
exploit this to spoof a website and trick the user into providing
credentia
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
2021-06-24
Published