CVE-2024-21491
svix vulnerable to Authentication Bypass
Versions of the package svix before 1.17.0 are vulnerable to Authentication Bypass due to an issue in the verify function where signatures of different lengths are incorrectly compared. An attacker can bypass signature verification by providing a shorter signature that matches the beginning of the actual signature.
Note:
The attacker would need to know a victim uses the Rust library for verification,no easy way to automatically check that; and uses webhooks by a service that uses Svix, and then figure out a way to craft a malicious payload that will actually include all of the correct identifiers needed to trick the receivers to cause actual issues.
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
- Low
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used 5.9
Versions of the package svix before 1.17.0 are vulnerable to Authentication Bypass due to an issue in the verify function where signatures of different lengths are incorrectly compared. An attacker can bypass signature verification by providing a shorter signature that matches the beginning of the actual signature.
Note:
The attacker would need to know a victim uses the Rust library for verification,no easy way to automatically check that; and uses webhooks by a service that uses Svix, and then figure out a way to craft a malicious payload that will actually include all of the correct identifiers needed to trick the receivers to cause actual issues.
- Record
CVE-2024-21491- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:N - Weakness
- CWE-288, CWE-288
- Updated
- 2026-11-02
EUVDEUVD-2024-0546 5.9
Versions of the package svix before 1.17.0 are vulnerable to Authentication Bypass due to an issue in the verify function where signatures of different lengths are incorrectly compared. An attacker can bypass signature verification by providing a shorter signature that matches the beginning of the actual signature.
Note:
The attacker would need to know a victim uses the Rust library for verification,no easy way to automatically check that; and uses webhooks by a service that uses Svix, and then figure out a way to craft a malicious payload that will actually include all of the correct identifiers needed to trick the receivers to cause actual issues.
- Record
EUVD-2024-0546- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-747x-5m58-mq97 6.8
svix vulnerable to Authentication Bypass
Versions of the package svix before 1.17.0 are vulnerable to Authentication Bypass due to an issue in the verify function where signatures of different lengths are incorrectly compared. An attacker can bypass signature verification by providing a shorter signature that matches the beginning of the actual signature.
Note:
The attacker would need to know a victim uses the Rust library for verification,no easy way to automatically check that; and uses webhooks by a service that uses Svix, and then figure out a way to craft a malicious payload that will actually include all of the correct identifiers needed to trick the receivers to cause actual issues.
- Record
GHSA-747x-5m58-mq97- CVSS 3.1
- 6.8 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N - Weakness
- CWE-288, CWE-347
- Updated
- 2026-11-02
GitHub AdvisoriesGHSA-w277-wpqf-rcfvNo score
Duplicate Advisory: Svix vulnerable to improper comparison of different-length signatures
Duplicate Advisory
This advisory has been withdrawn because it is a duplicate of GHSA-747x-5m58-mq97. This link is maintained to preserve external references.
Original Description
The Webhook::verify function incorrectly compared signatures of different lengths - the two signatures would only be compared up to the length of the shorter signature. This allowed an attacker to pass in v1, as the signature, which would always pass verification.
- Record
GHSA-w277-wpqf-rcfv- Updated
- 2026-11-02
NVD 5.9
Versions of the package svix before 1.17.0 are vulnerable to Authentication Bypass due to an issue in the verify function where signatures of different lengths are incorrectly compared. An attacker can bypass signature verification by providing a shorter signature that matches the beginning of the actual signature.
Note:
The attacker would need to know a victim uses the Rust library for verification,no easy way to automatically check that; and uses webhooks by a service that uses Svix, and then figure out a way to craft a malicious payload that will actually include all of the correct identifiers needed to trick the receivers to cause actual issues.
- Record
CVE-2024-21491- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:N - CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N - Weakness
- CWE-288, CWE-347
- Updated
- 2026-11-02
OSV 5.9
Versions of the package svix before 1.17.0 are vulnerable to Authentication Bypass due to an issue in the verify function where signatures of different lengths are incorrectly compared. An attacker can bypass signature verification by providing a shorter signature that matches the beginning of the actual signature.
Note:
The attacker would need to know a victim uses the Rust library for verification,no easy way to automatically check that; and uses webhooks by a service that uses Svix, and then figure out a way to craft a malicious payload that will actually include all of the correct identifiers needed to trick the receivers to cause actual issues.
- Record
CVE-2024-21491- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:N - Weakness
- CWE-288
- Updated
- 2026-11-02
OSVGHSA-747x-5m58-mq97 6.8
svix vulnerable to Authentication Bypass
Versions of the package svix before 1.17.0 are vulnerable to Authentication Bypass due to an issue in the verify function where signatures of different lengths are incorrectly compared. An attacker can bypass signature verification by providing a shorter signature that matches the beginning of the actual signature.
Note:
The attacker would need to know a victim uses the Rust library for verification,no easy way to automatically check that; and uses webhooks by a service that uses Svix, and then figure out a way to craft a malicious payload that will actually include all of the correct identifiers needed to trick the receivers to cause actual issues.
- Record
GHSA-747x-5m58-mq97- CVSS 3.1
- 6.8 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N - Weakness
- CWE-288, CWE-347
- Updated
- 2026-11-02
OSVGHSA-w277-wpqf-rcfvNo score
Duplicate Advisory: Svix vulnerable to improper comparison of different-length signatures
Duplicate Advisory
This advisory has been withdrawn because it is a duplicate of GHSA-747x-5m58-mq97. This link is maintained to preserve external references.
Original Description
The Webhook::verify function incorrectly compared signatures of different lengths - the two signatures would only be compared up to the length of the shorter signature. This allowed an attacker to pass in v1, as the signature, which would always pass verification.
- Record
GHSA-w277-wpqf-rcfv- Updated
- 2026-11-02
OSVRUSTSEC-2024-0010No score
Improper comparison of different-length signatures
The Webhook::verify function incorrectly compared signatures of
different lengths - the two signatures would only be compared up to
the length of the shorter signature. This allowed an attacker to
pass in v1, as the signature, which would always pass verification.
- Record
RUSTSEC-2024-0010- Updated
- 2026-11-02
Affected products
Affected packages
History
| Recorded | Changed | Sources |
|---|---|---|
| affected | ||
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2024-21491 is a medium vulnerability (CVSS 5.9) in Svix Svix-webhooks, published February 6, 2024. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.41%, the 35th percentile. Fixed in svix 1.17.0.