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CVE-2021-29949

When loading the shared library that provides the OTR protocol implementation, Thunderbird will...

7.8 HighFix available

When loading the shared library that provides the OTR protocol implementation, Thunderbird will initially attempt to open it using a filename that isn't distributed by Thunderbird. If a computer has already been infected with a malicious library of the alternative filename, and the malicious library has been copied to a directory that is contained in the search path for executable libraries, then Thunderbird will load the incorrect library. This vulnerability affects Thunderbird < 78.9.1.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
None
User interaction
Required

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

0.32%Down 0.3 points since Jun 25, 2021
90%50%10%1%

What each source reports

NVD Score used 7.8

When loading the shared library that provides the OTR protocol implementation, Thunderbird will initially attempt to open it using a filename that isn't distributed by Thunderbird. If a computer has already been infected with a malicious library of the alternative filename, and the malicious library has been copied to a directory that is contained in the search path for executable libraries, then Thunderbird will load the incorrect library. This vulnerability affects Thunderbird < 78.9.1.

Record
CVE-2021-29949
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CVSS 2.0
4.4 MediumAV:L/AC:M/Au:N/C:P/I:P/A:P
Weakness
CWE-427
Updated
2026-11-02
CVE List No score

When loading the shared library that provides the OTR protocol implementation, Thunderbird will initially attempt to open it using a filename that isn't distributed by Thunderbird. If a computer has already been infected with a malicious library of the alternative filename, and the malicious library has been copied to a directory that is contained in the search path for executable libraries, then Thunderbird will load the incorrect library. This vulnerability affects Thunderbird < 78.9.1.

Record
CVE-2021-29949
Updated
2026-11-02
EUVDEUVD-2021-16408 No score

When loading the shared library that provides the OTR protocol implementation, Thunderbird will initially attempt to open it using a filename that isn't distributed by Thunderbird. If a computer has already been infected with a malicious library of the alternative filename, and the malicious library has been copied to a directory that is contained in the search path for executable libraries, then Thunderbird will load the incorrect library. This vulnerability affects Thunderbird < 78.9.1.

Record
EUVD-2021-16408
Updated
2026-11-03
GitHub AdvisoriesGHSA-mhf4-98x7-2cw4 No score

When loading the shared library that provides the OTR protocol implementation, Thunderbird will...

When loading the shared library that provides the OTR protocol implementation, Thunderbird will initially attempt to open it using a filename that isn't distributed by Thunderbird. If a computer has already been infected with a malicious library of the alternative filename, and the malicious library has been copied to a directory that is contained in the search path for executable libraries, then Thunderbird will load the incorrect library. This vulnerability affects Thunderbird < 78.9.1.

Record
GHSA-mhf4-98x7-2cw4
Weakness
CWE-427
Updated
2026-11-02
OSV 7.8

When loading the shared library that provides the OTR protocol implementation, Thunderbird will initially attempt to open it using a filename that isn't distributed by Thunderbird. If a computer has already been infected with a malicious library of the alternative filename, and the malicious library has been copied to a directory that is contained in the search path for executable libraries, then Thunderbird will load the incorrect library. This vulnerability affects Thunderbird < 78.9.1.

Record
CVE-2021-29949
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVDEBIAN-CVE-2021-29949 7.8

When loading the shared library that provides the OTR protocol implementation, Thunderbird will initially attempt to open it using a filename that isn't distributed by Thunderbird. If a computer has already been infected with a malicious library of the alternative filename, and the malicious library has been copied to a directory that is contained in the search path for executable libraries, then Thunderbird will load the incorrect library. This vulnerability affects Thunderbird < 78.9.1.

Record
DEBIAN-CVE-2021-29949
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated
2026-11-02
Show 7 moreShow less
OSVRHSA-2021:1190 7.8

Red Hat Security Advisory: thunderbird security update

Record
RHSA-2021:1190
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVRHSA-2021:1192 7.8

Red Hat Security Advisory: thunderbird security update

Record
RHSA-2021:1192
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVRHSA-2021:1193 7.8

Red Hat Security Advisory: thunderbird security update

Record
RHSA-2021:1193
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVRHSA-2021:1201 7.8

Red Hat Security Advisory: thunderbird security update

Record
RHSA-2021:1201
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2021-29949 7.8

When loading the shared library that provides the OTR protocol implementation, Thunderbird will initially attempt to open it using a filename that isn't distributed by Thunderbird. If a computer has already been infected with a malicious library of the alternative filename, and the malicious library has been copied to a directory that is contained in the search path for executable libraries, then Thunderbird will load the incorrect library. This vulnerability affects Thunderbird < 78.9.1.

Record
UBUNTU-CVE-2021-29949
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVUSN-4995-1 No score

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 credentials. (CVE-2021-23984)

Multiple security issues were discovered in Thunderbird's OpenPGP integration. If a user were tricked into importing a specially crafted key in some circumstances, an attacker could potentially exploit this to cause a denial of service (inability to send encrypted email) or confuse the user. (CVE-2021-23991, CVE-2021-23992, CVE-2021-23993)

A use-after-free was discovered when Responsive Design Mode was enabled. If a user were tricked into opening a specially crafted website with Responsive Design Mode enabled, an attacker could potentially exploit this to cause a denial of service, or execute arbitrary code. (CVE-2021-23995)

It was discovered that Thunderbird mishandled ftp URLs with encoded newline characters. If a user were tricked into clicking on a specially crafted link, an attacker could potentially exploit this to send arbitrary FTP commands. (CVE-2021-24002)

It was discovered that Thunderbird wrote signatures to disk and read them back during verification. A local attacker could potentially exploit this to replace the data with another signature file. (CVE-2021-29948)

It was discovered that Thunderbird might load an alternative OTR library. If a user were tricked into copying a specially crafted library to one of Thunderbird's search paths, an attacker could potentially exploit this to execute arbitrary code. (CVE-2021-29949)

It was discovered that secret keys imported into Thunderbird were stored unencrypted. A local attacker could potentially exploit this to obtain private keys. (CVE-2021-29956)

It was discovered that Thunderbird did not indicate when an inline signed or encrypted message contained additional unprotected parts. (CVE-2021-29957)

Record
USN-4995-1
Updated
2026-11-02
OSVUSN-4995-2 No score

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 installing a specially crafted extension, an attacker could potentially exploit this to spoof a website and trick the user into providing credentials. (CVE-2021-23984)

Multiple security issues were discovered in Thunderbird's OpenPGP integration. If a user were tricked into importing a specially crafted key in some circumstances, an attacker could potentially exploit this to cause a denial of service (inability to send encrypted email) or confuse the user. (CVE-2021-23991, CVE-2021-23992, CVE-2021-23993)

A use-after-free was discovered when Responsive Design Mode was enabled. If a user were tricked into opening a specially crafted website with Responsive Design Mode enabled, an attacker could potentially exploit this to cause a denial of service, or execute arbitrary code. (CVE-2021-23995)

It was discovered that Thunderbird mishandled ftp URLs with encoded newline characters. If a user were tricked into clicking on a specially crafted link, an attacker could potentially exploit this to send arbitrary FTP commands. (CVE-2021-24002)

It was discovered that Thunderbird wrote signatures to disk and read them back during verification. A local attacker could potentially exploit this to replace the data with another signature file. (CVE-2021-29948)

It was discovered that Thunderbird might load an alternative OTR library. If a user were tricked into copying a specially crafted library to one of Thunderbird's search paths, an attacker could potentially exploit this to execute arbitrary code. (CVE-2021-29949)

It was discovered that secret keys imported into Thunderbird were stored unencrypted. A local attacker could potentially exploit this to obtain private keys. (CVE-2021-29956)

It was discovered that Thunderbird did not indicate when an inline signed or encrypted message contained additional unprotected parts. (CVE-2021-29957)

Record
USN-4995-2
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
thunderbird
Debian:12
before 1:78.10.0-1
1:78.10.0-1
thunderbird
Debian:13
before 1:78.10.0-1
1:78.10.0-1
thunderbird
Debian:14
before 1:78.10.0-1
1:78.10.0-1
thunderbird
Debian:9
From an advisory covering 13 CVEs
before 1:78.10.0-1~deb9u1, plus listed versions
1.5-41.5.0.2-11.5.0.2-21.5.0.2-31.5.0.4-1
Show 45 moreShow less
1.5.0.4-21.5.0.4-31.5.0.5-11.5.0.7-11.5.0.7-21:52.4.0-11:52.4.0-1~deb7u11:52.4.0-1~deb8u11:52.4.0-1~deb9u11:52.4.0-2~exp11:52.5.0-11:52.5.0-1~deb7u11:52.5.0-1~deb8u11:52.5.0-1~deb9u11:52.5.2-11:52.5.2-1~deb7u11:52.5.2-21:52.5.2-2~deb8u11:52.5.2-2~deb9u11:52.6.0-11:52.6.0-1+alpha.11:52.6.0-1+alpha.21:52.6.0-1~deb7u11:52.6.0-1~deb8u11:52.6.0-1~deb9u11:52.7.0-11:52.7.0-1~deb7u11:52.7.0-1~deb8u11:52.7.0-1~deb9u11:52.8.0-11:52.8.0-1~deb7u11:52.8.0-1~deb8u11:52.8.0-1~deb9u11:52.9.0-11:52.9.1-11:52.9.1-1~deb8u11:52.9.1-1~deb9u11:58.0~b3-11:60.0-11:60.0-21:60.0-2~deb9u11:60.0-31:60.0-3~deb9u11:60.0~b10-11:60.0~b2-1
1:78.10.0-1~deb9u1
thunderbird
Debian:10
From an advisory covering 13 CVEs
before 1:78.10.0-1~deb10u1, plus listed versions
1:60.7.2-11:60.8.0-11:60.8.0-1~deb10u11:60.8.0-1~deb8u11:60.8.0-1~deb9u1
Show 45 moreShow less
1:60.8.0-21:60.9.0-11:60.9.0-1~deb10u11:60.9.0-1~deb8u11:60.9.0-1~deb9u11:65.0~b1-11:66.0~b1-11:67.0~b3-11:68.0~b1-11:68.1.1-1~exp11:68.1.2-1~exp11:68.10.0-11:68.10.0-1~deb10u11:68.10.0-1~deb9u11:68.11.0-11:68.11.0-1~deb10u11:68.11.0-1~deb9u11:68.11.0-21:68.11.0-31:68.12.0-11:68.12.0-1~deb10u11:68.12.0-1~deb9u11:68.12.0-1~deb9u21:68.2.1-11:68.2.2-11:68.2.2-1~deb10u11:68.2.2-1~deb8u11:68.2.2-1~deb9u11:68.3.0-11:68.3.0-21:68.3.0-2~deb10u11:68.3.0-2~deb8u11:68.3.0-2~deb9u11:68.3.1-11:68.4.1-11:68.4.1-1~deb10u11:68.4.1-1~deb8u11:68.4.1-1~deb9u11:68.4.2-11:68.5.0-11:68.5.0-1~deb10u11:68.5.0-1~deb8u11:68.5.0-1~deb9u11:68.6.0-11:68.6.0-1~deb10u1
1:78.10.0-1~deb10u1
thunderbird
Red Hat:rhel_eus:8.1::appstream
From an advisory covering 5 CVEs
before 0:78.9.1-1.el8_1
0:78.9.1-1.el8_1
thunderbird-debuginfo
Red Hat:rhel_eus:8.1::appstream
From an advisory covering 5 CVEs
before 0:78.9.1-1.el8_1
0:78.9.1-1.el8_1
thunderbird-debugsource
Red Hat:rhel_eus:8.1::appstream
From an advisory covering 5 CVEs
before 0:78.9.1-1.el8_1
0:78.9.1-1.el8_1
thunderbird
Red Hat:enterprise_linux:7::client
From an advisory covering 5 CVEs
before 0:78.9.1-1.el7_9
0:78.9.1-1.el7_9
thunderbird-debuginfo
Red Hat:enterprise_linux:7::client
From an advisory covering 5 CVEs
before 0:78.9.1-1.el7_9
0:78.9.1-1.el7_9
Show 14 moreShow less
Affected packages
PackageAffectedFixed
thunderbird
Red Hat:enterprise_linux:7::server
From an advisory covering 5 CVEs
before 0:78.9.1-1.el7_9
0:78.9.1-1.el7_9
thunderbird-debuginfo
Red Hat:enterprise_linux:7::server
From an advisory covering 5 CVEs
before 0:78.9.1-1.el7_9
0:78.9.1-1.el7_9
thunderbird
Red Hat:enterprise_linux:7::workstation
From an advisory covering 5 CVEs
before 0:78.9.1-1.el7_9
0:78.9.1-1.el7_9
thunderbird-debuginfo
Red Hat:enterprise_linux:7::workstation
From an advisory covering 5 CVEs
before 0:78.9.1-1.el7_9
0:78.9.1-1.el7_9
thunderbird
Red Hat:enterprise_linux:8::appstream
From an advisory covering 5 CVEs
before 0:78.9.1-1.el8_3
0:78.9.1-1.el8_3
thunderbird-debuginfo
Red Hat:enterprise_linux:8::appstream
From an advisory covering 5 CVEs
before 0:78.9.1-1.el8_3
0:78.9.1-1.el8_3
thunderbird-debugsource
Red Hat:enterprise_linux:8::appstream
From an advisory covering 5 CVEs
before 0:78.9.1-1.el8_3
0:78.9.1-1.el8_3
thunderbird
Red Hat:rhel_eus:8.2::appstream
From an advisory covering 5 CVEs
before 0:78.9.1-1.el8_2
0:78.9.1-1.el8_2
thunderbird-debuginfo
Red Hat:rhel_eus:8.2::appstream
From an advisory covering 5 CVEs
before 0:78.9.1-1.el8_2
0:78.9.1-1.el8_2
thunderbird-debugsource
Red Hat:rhel_eus:8.2::appstream
From an advisory covering 5 CVEs
before 0:78.9.1-1.el8_2
0:78.9.1-1.el8_2
thunderbird
Ubuntu:18.04:LTS
before 1:78.11.0+build1-0ubuntu0.18.04.2, plus listed versions
1:52.4.0+build1-0ubuntu21:52.6.0+build1-0ubuntu11:52.7.0+build1-0ubuntu11:52.8.0+build1-0ubuntu0.18.04.11:52.9.1+build3-0ubuntu0.18.04.1
Show 16 moreShow less
1:60.2.1+build1-0ubuntu0.18.04.21:60.4.0+build2-0ubuntu0.18.04.11:60.5.1+build2-0ubuntu0.18.04.11:60.6.1+build2-0ubuntu0.18.04.11:60.7.0+build1-0ubuntu0.18.04.11:60.7.1+build1-0ubuntu0.18.04.11:60.7.2+build2-0ubuntu0.18.04.11:60.8.0+build1-0ubuntu0.18.04.11:60.9.0+build1-0ubuntu0.18.04.11:68.2.1+build1-0ubuntu0.18.04.11:68.2.2+build1-0ubuntu0.18.04.11:68.4.1+build1-0ubuntu0.18.04.11:68.7.0+build1-0ubuntu0.18.04.11:68.8.0+build2-0ubuntu0.18.04.21:68.10.0+build1-0ubuntu0.18.04.11:78.8.1+build1-0ubuntu0.18.04.1
1:78.11.0+build1-0ubuntu0.18.04.2
thunderbird
Ubuntu:20.04:LTS
before 1:78.11.0+build1-0ubuntu0.20.04.2, plus listed versions
1:68.1.2+build1-0ubuntu11:68.1.2+build1-0ubuntu21:68.2.1+build1-0ubuntu11:68.2.2+build1-0ubuntu11:68.3.0+build2-0ubuntu1
Show 11 moreShow less
1:68.3.1+build1-0ubuntu21:68.4.1+build1-0ubuntu11:68.4.2+build2-0ubuntu11:68.5.0+build1-0ubuntu11:68.6.0+build2-0ubuntu11:68.7.0+build1-0ubuntu11:68.7.0+build1-0ubuntu21:68.8.0+build2-0ubuntu0.20.04.21:68.10.0+build1-0ubuntu0.20.04.11:78.7.1+build1-0ubuntu0.20.04.11:78.8.1+build1-0ubuntu0.20.04.1
1:78.11.0+build1-0ubuntu0.20.04.2
thunderbird
Ubuntu:20.04:LTS
From an advisory covering 20 CVEs
before 1:78.11.0+build1-0ubuntu0.20.04.2, plus listed versions
1:68.1.2+build1-0ubuntu11:68.1.2+build1-0ubuntu21:68.2.1+build1-0ubuntu11:68.2.2+build1-0ubuntu11:68.3.0+build2-0ubuntu1
Show 11 moreShow less
1:68.3.1+build1-0ubuntu21:68.4.1+build1-0ubuntu11:68.4.2+build2-0ubuntu11:68.5.0+build1-0ubuntu11:68.6.0+build2-0ubuntu11:68.7.0+build1-0ubuntu11:68.7.0+build1-0ubuntu21:68.8.0+build2-0ubuntu0.20.04.21:68.10.0+build1-0ubuntu0.20.04.11:78.7.1+build1-0ubuntu0.20.04.11:78.8.1+build1-0ubuntu0.20.04.1
1:78.11.0+build1-0ubuntu0.20.04.2
thunderbird
Ubuntu:18.04:LTS
From an advisory covering 20 CVEs
before 1:78.11.0+build1-0ubuntu0.18.04.2, plus listed versions
1:52.4.0+build1-0ubuntu21:52.6.0+build1-0ubuntu11:52.7.0+build1-0ubuntu11:52.8.0+build1-0ubuntu0.18.04.11:52.9.1+build3-0ubuntu0.18.04.1
Show 16 moreShow less
1:60.2.1+build1-0ubuntu0.18.04.21:60.4.0+build2-0ubuntu0.18.04.11:60.5.1+build2-0ubuntu0.18.04.11:60.6.1+build2-0ubuntu0.18.04.11:60.7.0+build1-0ubuntu0.18.04.11:60.7.1+build1-0ubuntu0.18.04.11:60.7.2+build2-0ubuntu0.18.04.11:60.8.0+build1-0ubuntu0.18.04.11:60.9.0+build1-0ubuntu0.18.04.11:68.2.1+build1-0ubuntu0.18.04.11:68.2.2+build1-0ubuntu0.18.04.11:68.4.1+build1-0ubuntu0.18.04.11:68.7.0+build1-0ubuntu0.18.04.11:68.8.0+build2-0ubuntu0.18.04.21:68.10.0+build1-0ubuntu0.18.04.11:78.8.1+build1-0ubuntu0.18.04.1
1:78.11.0+build1-0ubuntu0.18.04.2

History

History
RecordedChangedSources
affected, facts
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-29949 is a high vulnerability (CVSS 7.8) in Mozilla Thunderbird, published April 22, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.32%, the 24th percentile. Fixed in thunderbird 1:78.10.0-1.

References

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Left out here: 211 versions. The JSON record has them.

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