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CVE-2021-29955

A transient execution vulnerability, named Floating Point Value Injection (FPVI) allowed an...

5.3 MediumFix available

A transient execution vulnerability, named Floating Point Value Injection (FPVI) allowed an attacker to leak arbitrary memory addresses and may have also enabled JIT type confusion attacks. (A related vulnerability, Speculative Code Store Bypass (SCSB), did not affect Firefox.). This vulnerability affects Firefox ESR < 78.9 and Firefox < 87.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
None
User interaction
Required

What an attacker can affect

Confidentiality
High
Integrity
None
Availability
None

Exploit likelihood

1.48%Unchanged since Jun 25, 2021
90%50%10%1%

What each source reports

NVD Score used 5.3

A transient execution vulnerability, named Floating Point Value Injection (FPVI) allowed an attacker to leak arbitrary memory addresses and may have also enabled JIT type confusion attacks. (A related vulnerability, Speculative Code Store Bypass (SCSB), did not affect Firefox.). This vulnerability affects Firefox ESR < 78.9 and Firefox < 87.

Record
CVE-2021-29955
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
CVSS 2.0
2.6 LowAV:N/AC:H/Au:N/C:P/I:N/A:N
Weakness
CWE-74
Updated
2026-11-02
CVE List No score

A transient execution vulnerability, named Floating Point Value Injection (FPVI) allowed an attacker to leak arbitrary memory addresses and may have also enabled JIT type confusion attacks. (A related vulnerability, Speculative Code Store Bypass (SCSB), did not affect Firefox.). This vulnerability affects Firefox ESR < 78.9 and Firefox < 87.

Record
CVE-2021-29955
Updated
2026-11-02
EUVDEUVD-2021-16414 No score

A transient execution vulnerability, named Floating Point Value Injection (FPVI) allowed an attacker to leak arbitrary memory addresses and may have also enabled JIT type confusion attacks. (A related vulnerability, Speculative Code Store Bypass (SCSB), did not affect Firefox.). This vulnerability affects Firefox ESR < 78.9 and Firefox < 87.

Record
EUVD-2021-16414
Updated
2026-11-03
GitHub AdvisoriesGHSA-2vp6-mvmx-fxh9 No score

A transient execution vulnerability, named Floating Point Value Injection (FPVI) allowed an...

A transient execution vulnerability, named Floating Point Value Injection (FPVI) allowed an attacker to leak arbitrary memory addresses and may have also enabled JIT type confusion attacks. (A related vulnerability, Speculative Code Store Bypass (SCSB), did not affect Firefox.). This vulnerability affects Firefox ESR < 78.9 and Firefox < 87.

Record
GHSA-2vp6-mvmx-fxh9
Weakness
CWE-74
Updated
2026-11-02
OSV 5.3

A transient execution vulnerability, named Floating Point Value Injection (FPVI) allowed an attacker to leak arbitrary memory addresses and may have also enabled JIT type confusion attacks. (A related vulnerability, Speculative Code Store Bypass (SCSB), did not affect Firefox.). This vulnerability affects Firefox ESR < 78.9 and Firefox < 87.

Record
CVE-2021-29955
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
Updated
2026-11-02
OSVDEBIAN-CVE-2021-29955 5.3

A transient execution vulnerability, named Floating Point Value Injection (FPVI) allowed an attacker to leak arbitrary memory addresses and may have also enabled JIT type confusion attacks. (A related vulnerability, Speculative Code Store Bypass (SCSB), did not affect Firefox.). This vulnerability affects Firefox ESR < 78.9 and Firefox < 87.

Record
DEBIAN-CVE-2021-29955
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
Updated
2026-11-02
OSVOESA-2023-1673 10.0

firefox security update

Mozilla Firefox is a standalone web browser, designed for standards compliance and performance. Its functionality can be enhanced via a plethora of extensions.

Mozilla Firefox is an open-source web browser, designed for standards compliance, performance and portability.

Security Fix(es):

Mozilla developers reported memory safety bugs present in Firefox for Android 79. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 80, Firefox ESR < 78.2, Thunderbird < 78.2, and Firefox for Android < 80.(CVE-2020-15670)

Mozilla developers reported memory safety bugs present in Firefox 80 and Firefox ESR 78.2. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 81, Thunderbird < 78.3, and Firefox ESR < 78.3.(CVE-2020-15673)

Mozilla developers reported memory safety bugs present in Firefox 80. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 81.(CVE-2020-15674)

When processing surfaces, the lifetime may outlive a persistent buffer leading to memory corruption and a potentially exploitable crash. This vulnerability affects Firefox < 81.(CVE-2020-15675)

If a valid external protocol handler was referenced in an image tag, the resulting broken image size could be distinguished from a broken image size of a non-existent protocol handler. This allowed an attacker to successfully probe whether an external protocol handler was registered. This vulnerability affects Firefox < 82.(CVE-2020-15680)

When multiple WASM threads had a reference to a module, and were looking up exported functions, one WASM thread could have overwritten another's entry in a shared stub table, resulting in a potentially exploitable crash. This vulnerability affects Firefox < 82.(CVE-2020-15681)

When a link to an external protocol was clicked, a prompt was presented that allowed the user to choose what application to open it in. An attacker could induce that prompt to be associated with an origin they didn't control, resulting in a spoofing attack. This was fixed by changing external protocol prompts to be tab-modal while also ensuring they could not be incorrectly associated with a different origin. This vulnerability affects Firefox < 82.(CVE-2020-15682)

Mozilla developers and community members reported memory safety bugs present in Firefox 81 and Firefox ESR 78.3. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox ESR < 78.4, Firefox < 82, and Thunderbird < 78.4.(CVE-2020-15683)

Mozilla developers reported memory safety bugs present in Firefox 81. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 82.(CVE-2020-15684)

Side-channel information leakage in graphics in Google Chrome prior to 87.0.4280.66 allowed a remote attacker to leak cross-origin data via a crafted HTML page.(CVE-2020-16012)

Use after free in WebRTC in Google Chrome prior to 88.0.4324.96 allowed a remote attacker to potentially exploit heap corruption via a crafted SCTP packet.(CVE-2020-16044)

In certain circumstances, the MCallGetProperty opcode can be emitted with unmet assumptions resulting in an exploitable use-after-free condition. This vulnerability affects Firefox < 82.0.3, Firefox ESR < 78.4.1, and Thunderbird < 78.4.2.(CVE-2020-26950)

(CVE-2020-26951)

(CVE-2020-26953) …

Record
OESA-2023-1673
CVSS 3.1
10.0 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Updated
2026-11-02
OSVOESA-2023-1674 10.0

firefox security update

Mozilla Firefox is a standalone web browser, designed for standards compliance and performance. Its functionality can be enhanced via a plethora of extensions.

Mozilla Firefox is an open-source web browser, designed for standards compliance, performance and portability.

Security Fix(es):

Mozilla developers reported memory safety bugs present in Firefox for Android 79. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 80, Firefox ESR < 78.2, Thunderbird < 78.2, and Firefox for Android < 80.(CVE-2020-15670)

Mozilla developers reported memory safety bugs present in Firefox 80 and Firefox ESR 78.2. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 81, Thunderbird < 78.3, and Firefox ESR < 78.3.(CVE-2020-15673)

Mozilla developers reported memory safety bugs present in Firefox 80. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 81.(CVE-2020-15674)

When processing surfaces, the lifetime may outlive a persistent buffer leading to memory corruption and a potentially exploitable crash. This vulnerability affects Firefox < 81.(CVE-2020-15675)

If a valid external protocol handler was referenced in an image tag, the resulting broken image size could be distinguished from a broken image size of a non-existent protocol handler. This allowed an attacker to successfully probe whether an external protocol handler was registered. This vulnerability affects Firefox < 82.(CVE-2020-15680)

When multiple WASM threads had a reference to a module, and were looking up exported functions, one WASM thread could have overwritten another's entry in a shared stub table, resulting in a potentially exploitable crash. This vulnerability affects Firefox < 82.(CVE-2020-15681)

When a link to an external protocol was clicked, a prompt was presented that allowed the user to choose what application to open it in. An attacker could induce that prompt to be associated with an origin they didn't control, resulting in a spoofing attack. This was fixed by changing external protocol prompts to be tab-modal while also ensuring they could not be incorrectly associated with a different origin. This vulnerability affects Firefox < 82.(CVE-2020-15682)

Mozilla developers and community members reported memory safety bugs present in Firefox 81 and Firefox ESR 78.3. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox ESR < 78.4, Firefox < 82, and Thunderbird < 78.4.(CVE-2020-15683)

Mozilla developers reported memory safety bugs present in Firefox 81. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 82.(CVE-2020-15684)

Side-channel information leakage in graphics in Google Chrome prior to 87.0.4280.66 allowed a remote attacker to leak cross-origin data via a crafted HTML page.(CVE-2020-16012)

Use after free in WebRTC in Google Chrome prior to 88.0.4324.96 allowed a remote attacker to potentially exploit heap corruption via a crafted SCTP packet.(CVE-2020-16044)

In certain circumstances, the MCallGetProperty opcode can be emitted with unmet assumptions resulting in an exploitable use-after-free condition. This vulnerability affects Firefox < 82.0.3, Firefox ESR < 78.4.1, and Thunderbird < 78.4.2.(CVE-2020-26950)

(CVE-2020-26951)

(CVE-2020-26953) …

Record
OESA-2023-1674
CVSS 3.1
10.0 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2021-29955 5.3

A transient execution vulnerability, named Floating Point Value Injection (FPVI) allowed an attacker to leak arbitrary memory addresses and may have also enabled JIT type confusion attacks. (A related vulnerability, Speculative Code Store Bypass (SCSB), did not affect Firefox.). This vulnerability affects Firefox ESR < 78.9 and Firefox < 87.

Record
UBUNTU-CVE-2021-29955
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
firefox-esr
Debian:12
before 78.9.0esr-1
78.9.0esr-1
firefox-esr
Debian:13
before 78.9.0esr-1
78.9.0esr-1
firefox-esr
Debian:14
before 78.9.0esr-1
78.9.0esr-1
firefox-esr
Debian:9
From an advisory covering 5 CVEs
before 78.9.0esr-1~deb9u1, plus listed versions
45.9.0esr-152.0.1esr-152.0.2esr-152.0esr-152.1.0esr-1
Show 45 moreShow less
52.2.0esr-152.2.0esr-1~deb7u152.2.0esr-1~deb8u152.2.0esr-1~deb9u152.2.0esr-252.3.0esr-152.3.0esr-1~deb7u152.3.0esr-1~deb8u152.3.0esr-1~deb8u252.3.0esr-1~deb9u152.3.0esr-252.4.0esr-1~deb8u152.4.0esr-1~deb9u152.4.0esr-252.4.0esr-2~deb7u152.5.0esr-152.5.0esr-1~deb7u152.5.0esr-1~deb8u152.5.0esr-1~deb9u152.5.2esr-152.5.2esr-1~deb7u152.5.2esr-1~deb8u152.5.2esr-1~deb9u152.5.3esr-152.6.0esr-152.6.0esr-1~deb7u152.6.0esr-1~deb8u152.6.0esr-1~deb9u152.6.0esr-252.6.0esr-2+alpha.152.6.0esr-2+alpha.252.7.0esr-152.7.0esr-1~deb8u152.7.0esr-1~deb9u152.7.1esr-152.7.1esr-1~deb7u152.7.1esr-1~deb8u152.7.1esr-1~deb9u152.7.2esr-152.7.2esr-1~deb7u152.7.2esr-1~deb8u152.7.2esr-1~deb9u152.7.3esr-152.7.3esr-1~deb7u152.7.3esr-1~deb8u1
78.9.0esr-1~deb9u1
firefox-esr
Debian:10
From an advisory covering 6 CVEs
before 78.9.0esr-1~deb10u1, plus listed versions
60.7.2esr-160.8.0esr-160.8.0esr-1~deb10u160.8.0esr-1~deb8u160.8.0esr-1~deb9u1
Show 45 moreShow less
60.9.0esr-1~deb10u160.9.0esr-1~deb8u160.9.0esr-1~deb8u260.9.0esr-1~deb9u168.0.2esr-168.1.0esr-168.10.0esr-168.10.0esr-1~deb10u168.10.0esr-1~deb9u168.11.0esr-168.11.0esr-1~deb10u168.11.0esr-1~deb9u168.12.0esr-168.12.0esr-1~deb10u168.12.0esr-1~deb9u168.2.0esr-168.2.0esr-1~deb10u168.2.0esr-1~deb8u168.2.0esr-1~deb9u168.2.0esr-1~deb9u268.3.0esr-168.3.0esr-1~deb10u168.3.0esr-1~deb8u168.3.0esr-1~deb9u168.4.0esr-168.4.0esr-1~deb10u168.4.0esr-1~deb8u168.4.0esr-1~deb9u168.4.1esr-168.4.1esr-1~deb10u168.4.1esr-1~deb8u168.4.1esr-1~deb9u168.4.2esr-168.5.0esr-168.5.0esr-1~deb10u168.5.0esr-1~deb8u168.5.0esr-1~deb9u168.6.0esr-168.6.0esr-1~deb10u168.6.0esr-1~deb8u168.6.0esr-1~deb9u168.6.1esr-168.6.1esr-1~deb10u168.6.1esr-1~deb9u168.7.0esr-1
78.9.0esr-1~deb10u1
firefox
openEuler:22.03-LTS
From an advisory covering 289 CVEs
before 102.14.0-1.oe2203
102.14.0-1.oe2203
firefox
openEuler:22.03-LTS-SP1
From an advisory covering 289 CVEs
before 102.14.0-1.oe2203sp1
102.14.0-1.oe2203sp1
firefox
Ubuntu:18.04:LTS
before 87.0+build3-0ubuntu0.18.04.2, plus listed versions
56.0+build6-0ubuntu157.0.1+build2-0ubuntu159.0.1+build1-0ubuntu159.0.2+build1-0ubuntu160.0+build2-0ubuntu1
Show 45 moreShow less
60.0.1+build2-0ubuntu0.18.04.160.0.2+build1-0ubuntu0.18.04.161.0+build3-0ubuntu0.18.04.161.0.1+build1-0ubuntu0.18.04.162.0+build2-0ubuntu0.18.04.362.0+build2-0ubuntu0.18.04.462.0+build2-0ubuntu0.18.04.562.0.3+build1-0ubuntu0.18.04.163.0+build2-0ubuntu0.18.04.263.0.3+build1-0ubuntu0.18.04.164.0+build3-0ubuntu0.18.04.165.0+build2-0ubuntu0.18.04.165.0.1+build2-0ubuntu0.18.04.166.0+build3-0ubuntu0.18.04.166.0.1+build1-0ubuntu0.18.04.166.0.2+build1-0ubuntu0.18.04.166.0.3+build1-0ubuntu0.18.04.166.0.4+build3-0ubuntu0.18.04.166.0.5+build1-0ubuntu0.18.04.167.0+build2-0ubuntu0.18.04.167.0.1+build1-0ubuntu0.18.04.167.0.2+build2-0ubuntu0.18.04.167.0.3+build1-0ubuntu0.18.04.167.0.4+build1-0ubuntu0.18.04.168.0+build3-0ubuntu0.18.04.168.0.1+build1-0ubuntu0.18.04.168.0.2+build1-0ubuntu0.18.04.169.0+build2-0ubuntu0.18.04.169.0.1+build1-0ubuntu0.18.04.169.0.2+build1-0ubuntu0.18.04.170.0+build2-0ubuntu0.18.04.170.0.1+build1-0ubuntu0.18.04.171.0+build5-0ubuntu0.18.04.172.0.1+build1-0ubuntu0.18.04.172.0.2+build1-0ubuntu0.18.04.173.0+build3-0ubuntu0.18.04.173.0.1+build1-0ubuntu0.18.04.174.0+build3-0ubuntu0.18.04.174.0.1+build1-0ubuntu0.18.04.175.0+build3-0ubuntu0.18.04.176.0+build2-0ubuntu0.18.04.176.0.1+build1-0ubuntu0.18.04.177.0.1+build1-0ubuntu0.18.04.178.0.1+build1-0ubuntu0.18.04.178.0.2+build2-0ubuntu0.18.04.1
87.0+build3-0ubuntu0.18.04.2
mozjs52
Ubuntu:18.04:LTS
All versions, plus listed versions
52.3.1-0ubuntu352.3.1-7fakesync152.8.1-0ubuntu0.18.04.152.9.1-0ubuntu0.18.04.1
None known
mozjs38
Ubuntu:18.04:LTS
All versions, plus listed versions
38.8.0~repack1-0ubuntu138.8.0~repack1-0ubuntu338.8.0~repack1-0ubuntu4
None known
mozjs68
Ubuntu:20.04:LTS
All versions, plus listed versions
68.5.0-1~fakesync68.5.0-2~fakesync68.6.0-168.6.0-1ubuntu1
None known
mozjs52
Ubuntu:20.04:LTS
All versions, plus listed versions
52.9.1-1build152.9.1-1ubuntu3
None known
mozjs78
Ubuntu:22.04:LTS
All versions, plus listed versions
78.13.0-178.15.0-278.15.0-4ubuntu1
None known

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-2021-29955 is a medium vulnerability (CVSS 5.3) in Mozilla Firefox, published March 24, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.48%, the 74th percentile. Fixed in firefox-esr 78.9.0esr-1.

References

Show 194 moreShow less
This page doesn't list everything

Left out here: 209 versions, 100 references and the rest of 2 source descriptions. The JSON record has them.

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