CVE-2021-36155
Uncontrolled Resource Consumption in LengthPrefixedMessageReader
LengthPrefixedMessageReader in gRPC Swift 1.1.0 and earlier allocates buffers of arbitrary length, which allows remote attackers to cause uncontrolled resource consumption and deny service.
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
LengthPrefixedMessageReader in gRPC Swift 1.1.0 and earlier allocates buffers of arbitrary length, which allows remote attackers to cause uncontrolled resource consumption and deny service.
- Record
CVE-2021-36155- 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-770
- Updated
- 2026-11-02
CVE List No score
LengthPrefixedMessageReader in gRPC Swift 1.1.0 and earlier allocates buffers of arbitrary length, which allows remote attackers to cause uncontrolled resource consumption and deny service.
- Record
CVE-2021-36155- Updated
- 2026-11-02
EUVDEUVD-2023-1886 No score
LengthPrefixedMessageReader in gRPC Swift 1.1.0 and earlier allocates buffers of arbitrary length, which allows remote attackers to cause uncontrolled resource consumption and deny service.
- Record
EUVD-2023-1886- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-rxmj-hg9v-vp3p
Uncontrolled Resource Consumption in LengthPrefixedMessageReader
Impact
Affected gRPC Swift clients and servers are vulnerable to uncontrolled resource consumption attacks. Excessive memory may be allocated when parsing messages. This can lead to a denial of service.
Patches
The problem has been fixed in 1.2.0.
Workarounds
No workaround is available. Users must upgrade.
- Record
GHSA-rxmj-hg9v-vp3p- 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 - Weakness
- CWE-120, CWE-770
- Updated
- 2026-11-02
OSV
LengthPrefixedMessageReader in gRPC Swift 1.1.0 and earlier allocates buffers of arbitrary length, which allows remote attackers to cause uncontrolled resource consumption and deny service.
- Record
CVE-2021-36155- 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
OSVGHSA-rxmj-hg9v-vp3p
Uncontrolled Resource Consumption in LengthPrefixedMessageReader
Impact
Affected gRPC Swift clients and servers are vulnerable to uncontrolled resource consumption attacks. Excessive memory may be allocated when parsing messages. This can lead to a denial of service.
Patches
The problem has been fixed in 1.2.0.
Workarounds
No workaround is available. Users must upgrade.
- Record
GHSA-rxmj-hg9v-vp3p- 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 - Weakness
- CWE-120, CWE-770
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
github.com/grpc/grpc-swiftSwiftURL |
before 1.2.0 | 1.2.0 |
History
| Recorded | Changed | Sources |
|---|---|---|
| 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-2021-36155 is a high vulnerability (CVSS 7.5) in Linuxfoundation Grpc Swift, published July 9, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.08%, the 81st percentile. Fixed in github.com/grpc/grpc-swift 1.2.0.
References
github.com/grpc/grpc-swift/releases
bugs.chromium.org/p/oss-fuzz/issues/detail?id=35303
nvd.nist.gov/vuln/detail/CVE-2021-36155