CVE-2021-34550
An issue was discovered in Tor before 0.4.6.5, aka TROVE-2021-006. The v3 onion service...
An issue was discovered in Tor before 0.4.6.5, aka TROVE-2021-006. The v3 onion service descriptor parsing allows out-of-bounds memory access, and a client crash, via a crafted onion service descriptor
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
NVD Score used
7.5
An issue was discovered in Tor before 0.4.6.5, aka TROVE-2021-006. The v3 onion service descriptor parsing allows out-of-bounds memory access, and a client crash, via a crafted onion service descriptor
- Record
CVE-2021-34550- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:N/I:N/A:P - Weakness
- CWE-119
- Updated
- 2026-11-02
CVE List No score
An issue was discovered in Tor before 0.4.6.5, aka TROVE-2021-006. The v3 onion service descriptor parsing allows out-of-bounds memory access, and a client crash, via a crafted onion service descriptor
- Record
CVE-2021-34550- Updated
- 2026-11-02
EUVDEUVD-2021-21202 No score
An issue was discovered in Tor before 0.4.6.5, aka TROVE-2021-006. The v3 onion service descriptor parsing allows out-of-bounds memory access, and a client crash, via a crafted onion service descriptor
- Record
EUVD-2021-21202- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-28mq-w7hj-99g5 No score
An issue was discovered in Tor before 0.4.6.5, aka TROVE-2021-006. The v3 onion service...
An issue was discovered in Tor before 0.4.6.5, aka TROVE-2021-006. The v3 onion service descriptor parsing allows out-of-bounds memory access, and a client crash, via a crafted onion service descriptor
- Record
GHSA-28mq-w7hj-99g5- Weakness
- CWE-119
- Updated
- 2026-11-02
OSVALPINE-CVE-2021-34550
7.5
An issue was discovered in Tor before 0.4.6.5, aka TROVE-2021-006. The v3 onion service descriptor parsing allows out-of-bounds memory access, and a client crash, via a crafted onion service descriptor
- Record
ALPINE-CVE-2021-34550- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-03
OSV
7.5
An issue was discovered in Tor before 0.4.6.5, aka TROVE-2021-006. The v3 onion service descriptor parsing allows out-of-bounds memory access, and a client crash, via a crafted onion service descriptor
- Record
CVE-2021-34550- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
Show 7 moreShow less
OSVDEBIAN-CVE-2021-34550
7.5
An issue was discovered in Tor before 0.4.6.5, aka TROVE-2021-006. The v3 onion service descriptor parsing allows out-of-bounds memory access, and a client crash, via a crafted onion service descriptor
- Record
DEBIAN-CVE-2021-34550- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2021-34550
7.5
An issue was discovered in Tor before 0.4.6.5, aka TROVE-2021-006. The v3 onion service descriptor parsing allows out-of-bounds memory access, and a client crash, via a crafted onion service descriptor
- Record
UBUNTU-CVE-2021-34550- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVMGASA-2021-0293 No score
Updated tor package fixes security vulnerabilities
Don't allow relays to spoof RELAY_END or RELAY_RESOLVED cell on half-closed streams. Previously, clients failed to validate which hop sent these cells: this would allow a relay on a circuit to end a stream that wasn't actually built with it (CVE-2021-34548).
hashtable-based CPU denial-of-service attack against relays (CVE-2021-34549).
out-of-bounds memory access in v3 onion service descriptor parsing (CVE-2021-34550).
See also upstream release notes for included other bugfixes.
This package also fixes an error in tor package's un-install script (mga#29158).
- Record
MGASA-2021-0293- Updated
- 2026-11-02
OSVopenSUSE-SU-2021:0926-1 No score
Security update for tor
This update for tor fixes the following issues:
tor 0.4.5.9
- Don't allow relays to spoof RELAY_END or RELAY_RESOLVED cell (CVE-2021-34548, boo#1187322)
- Detect more failure conditions from the OpenSSL RNG code (boo#1187323)
- Resist a hashtable-based CPU denial-of-service attack against relays (CVE-2021-34549, boo#1187324)
- Fix an out-of-bounds memory access in v3 onion service descriptor parsing (CVE-2021-34550, boo#1187325)
tor 0.4.5.8
- https://lists.torproject.org/pipermail/tor-announce/2021-May/000219.html
- allow Linux sandbox with Glibc 2.33
- work with autoconf 2.70+
- several other minor features and bugfixes (see announcement)
- Fix logging issue due to systemd picking up stdout - boo#1181244 Continue to log notices to syslog by default.
- Record
openSUSE-SU-2021:0926-1- Updated
- 2026-11-02
OSVopenSUSE-SU-2021:0941-1 No score
Security update for tor
This update for tor fixes the following issues:
tor 0.4.5.9
- Don't allow relays to spoof RELAY_END or RELAY_RESOLVED cell (CVE-2021-34548, boo#1187322)
- Detect more failure conditions from the OpenSSL RNG code (boo#1187323)
- Resist a hashtable-based CPU denial-of-service attack against relays (CVE-2021-34549, boo#1187324)
- Fix an out-of-bounds memory access in v3 onion service descriptor parsing (CVE-2021-34550, boo#1187325)
tor 0.4.5.8
- https://lists.torproject.org/pipermail/tor-announce/2021-May/000219.html
- allow Linux sandbox with Glibc 2.33
- work with autoconf 2.70+
- several other minor features and bugfixes (see announcement)
- Fix logging issue due to systemd picking up stdout - boo#1181244 Continue to log notices to syslog by default.
This update was imported from the openSUSE:Leap:15.2:Update update project.
- Record
openSUSE-SU-2021:0941-1- Updated
- 2026-11-02
OSVopenSUSE-SU-2024:11469-1 No score
tor-0.4.6.7-2.2 on GA media
These are all security issues fixed in the tor-0.4.6.7-2.2 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2024:11469-1- Updated
- 2026-11-02
OSVUSN-5036-1 No score
tor vulnerabilities
It was discovered that Tor incorrectly handled certain memory operations. A remote attacker could use this issue to cause a denial of service. This issue only affected Ubuntu 18.04 ESM. (CVE-2019-8955)
It was discovered that Tor did not properly handle the input length to dump_desc() function. A remote attacker could use this issue to cause a denial of service. This issue only affected Ubuntu 16.04 ESM, Ubuntu 18.04 ESM and Ubuntu 20.04 ESM. (CVE-2021-28089)
It was discovered that Tor did not properly sanitize the relay nickname in dirvote_add_signatures_to_pending_consensus() function. An attacker could possibly use this issue to cause an assertion failure and then cause a denial of service. (CVE-2021-28090)
It was discovered that Tor did not properly validate the layer hint on half-open streams. A remote attacker could possibly use this issue to bypass the access control, leading to remote code execution. This issue only affected Ubuntu 20.04 ESM. (CVE-2021-34548)
It was discovered that Tor was using an insecure hash function. A remote attacker could use this issue to cause a denial of service. This issue only affected Ubuntu 16.04 ESM, Ubuntu 18.04 ESM and Ubuntu 20.04 ESM. (CVE-2021-34549)
It was discovered that Tor did not properly manage memory under certain circumstances. If a user were tricked into opening a specially crafted request, a remote attacker could possibly use this issue to cause a crash, resulting in a denial of service, or possibly reading sensitive data. This issue only affected Ubuntu 18.04 ESM and Ubuntu 20.04 ESM. (CVE-2021-34550)
It was discovered that Tor mishandles the relationship between batch-signature verification and single-signature verification. An attacker could possibly use this issue to cause an assertion failure and then cause a denial of service. This issue only affected Ubuntu 16.04 ESM, Ubuntu 18.04 ESM and Ubuntu 20.04 ESM. (CVE-2021-38385)
- Record
USN-5036-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
torAlpine:v3.11 |
0.4.0.0 up to 0.4.4.9-r0 | 0.4.4.9-r0 |
torAlpine:v3.12 |
0.4.0.0 up to 0.4.4.9-r0 | 0.4.4.9-r0 |
torDebian:12 |
before 0.4.5.9-1 | 0.4.5.9-1 |
torDebian:13 |
before 0.4.5.9-1 | 0.4.5.9-1 |
torDebian:14 |
before 0.4.5.9-1 | 0.4.5.9-1 |
torDebian:10 From an advisory covering 3 CVEs |
before 0.3.5.15-1, plus listed versions 0.3.5.10-10.3.5.10-1~bpo9+10.3.5.12-10.3.5.14-10.3.5.8-1 |
0.3.5.15-1 |
torMageia:7 From an advisory covering 3 CVEs |
before 0.3.5.15-1.1.mga7 | 0.3.5.15-1.1.mga7 |
torMageia:8 From an advisory covering 3 CVEs |
before 0.3.5.15-1.1.mga8 | 0.3.5.15-1.1.mga8 |
torUbuntu:Pro:18.04:LTS |
before 0.3.2.10-1ubuntu0.2~esm2, plus listed versions 0.3.0.10-10.3.1.8-20.3.1.9-10.3.2.9-10.3.2.9-1build10.3.2.10-10.3.2.10-1ubuntu0.10.3.2.10-1ubuntu0.2~esm1 |
0.3.2.10-1ubuntu0.2~esm2 |
torUbuntu:Pro:20.04:LTS |
before 0.4.2.7-1ubuntu0.1~esm1, plus listed versions 0.4.1.5-10.4.1.5-1build10.4.1.6-10.4.2.5-10.4.2.6-10.4.2.7-1 |
0.4.2.7-1ubuntu0.1~esm1 |
Show 7 moreShow less
| Package | Affected | Fixed |
|---|---|---|
torUbuntu:Pro:14.04:LTS From an advisory covering 7 CVEs |
before 0.2.4.27-1ubuntu0.1+esm2, plus listed versions 0.2.3.25-10.2.4.19-10.2.4.20-10.2.4.27-1build0.14.04.10.2.4.27-1ubuntu0.10.2.4.27-1ubuntu0.1+esm1 |
0.2.4.27-1ubuntu0.1+esm2 |
torUbuntu:Pro:16.04:LTS From an advisory covering 7 CVEs |
before 0.2.9.14-1ubuntu1~16.04.3+esm1, plus listed versions 0.2.6.10-1ubuntu20.2.7.6-1ubuntu10.2.9.11-1ubuntu1~16.04.10.2.9.14-1ubuntu1~16.04.10.2.9.14-1ubuntu1~16.04.20.2.9.14-1ubuntu1~16.04.3 |
0.2.9.14-1ubuntu1~16.04.3+esm1 |
torUbuntu:Pro:18.04:LTS From an advisory covering 7 CVEs |
before 0.3.2.10-1ubuntu0.2~esm2, plus listed versions 0.3.0.10-10.3.1.8-20.3.1.9-10.3.2.9-10.3.2.9-1build10.3.2.10-10.3.2.10-1ubuntu0.10.3.2.10-1ubuntu0.2~esm1 |
0.3.2.10-1ubuntu0.2~esm2 |
torUbuntu:Pro:20.04:LTS From an advisory covering 7 CVEs |
before 0.4.2.7-1ubuntu0.1~esm1, plus listed versions 0.4.1.5-10.4.1.5-1build10.4.1.6-10.4.2.5-10.4.2.6-10.4.2.7-1 |
0.4.2.7-1ubuntu0.1~esm1 |
toropenSUSE:Leap 15.2 From an advisory covering 3 CVEs |
before 0.4.5.9-lp152.2.12.1 | 0.4.5.9-lp152.2.12.1 |
torSUSE:Package Hub 15 SP2 From an advisory covering 3 CVEs |
before 0.4.5.9-bp152.2.12.1 | 0.4.5.9-bp152.2.12.1 |
toropenSUSE:Tumbleweed From an advisory covering 22 CVEs |
before 0.4.6.7-2.2 | 0.4.6.7-2.2 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts | ||
| affected, aliases, references | OSV | |
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-34550 is a high vulnerability (CVSS 7.5) in Torproject Tor, published June 18, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.56%, the 75th percentile. Fixed in tor 0.4.4.9-r0.
References
gitlab.torproject.org/tpo/core/tor/-/issues/40392
blog.torproject.org/node/2041
security.gentoo.org/glsa/202107-25
nvd.nist.gov/vuln/detail/CVE-2021-34550
github.com/advisories/GHSA-28mq-w7hj-99g5
security.alpinelinux.org/vuln/CVE-2021-34550
Show 45 moreShow less
security-tracker.debian.org/tracker/CVE-2021-34550
advisories.mageia.org/MGASA-2021-0293.html
bugs.mageia.org/show_bug.cgi?id=29136
bugs.mageia.org/show_bug.cgi?id=29158
lists.fedoraproject.org/archives/list/[email protected]/thread/RST7YTNTKJURIR2QVIJMEBXWW2YHETRX
ubuntu.com/security/CVE-2021-34550
gitlab.torproject.org/tpo/core/tor/-/commit/f57b5c48e0aa01acd84a194fe4657a0d1cee04cf
ubuntu.com/security/notices/USN-5036-1
cve.org/CVERecord?id=CVE-2021-34550
ubuntu.com/security/CVE-2019-8955
ubuntu.com/security/CVE-2021-28089
ubuntu.com/security/CVE-2021-28090
ubuntu.com/security/CVE-2021-34548
ubuntu.com/security/CVE-2021-34549
ubuntu.com/security/CVE-2021-38385
lists.opensuse.org/archives/list/[email protected]/thread/GJI5DAQGLSGJLTAEBDK3BJ65DR3SJHCE
bugzilla.suse.com/1179331
bugzilla.suse.com/1181244
bugzilla.suse.com/1187322
bugzilla.suse.com/1187323
bugzilla.suse.com/1187324
bugzilla.suse.com/1187325
suse.com/security/cve/CVE-2021-34548
suse.com/security/cve/CVE-2021-34549
suse.com/security/cve/CVE-2021-34550
lists.opensuse.org/archives/list/[email protected]/thread/553MAZKSU2F6B7N6LTWA5YMHITLEL3HL
suse.com/security/cve/CVE-2016-1254
suse.com/security/cve/CVE-2017-0375
suse.com/security/cve/CVE-2017-0376
suse.com/security/cve/CVE-2017-0377
suse.com/security/cve/CVE-2017-0380
suse.com/security/cve/CVE-2017-8819
suse.com/security/cve/CVE-2017-8820
suse.com/security/cve/CVE-2017-8821
suse.com/security/cve/CVE-2017-8822
suse.com/security/cve/CVE-2017-8823
suse.com/security/cve/CVE-2018-0490
suse.com/security/cve/CVE-2018-0491
suse.com/security/cve/CVE-2019-8955
suse.com/security/cve/CVE-2020-10592
suse.com/security/cve/CVE-2020-10593
suse.com/security/cve/CVE-2020-15572
suse.com/security/cve/CVE-2021-28089
suse.com/security/cve/CVE-2021-28090
suse.com/security/cve/CVE-2021-38385