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CVE-2024-21491

svix vulnerable to Authentication Bypass

5.9 MediumFix available

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

0.41%Up 0.4 points since Feb 13, 2024
90%50%10%1%

What each source reports

CVE List Score used5.9

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 MediumCVSS: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-2024-05465.9

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 MediumCVSS: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-mq976.8

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 MediumCVSS: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
NVD5.9

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 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:N
CVSS 3.1
6.5 MediumCVSS: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
OSV5.9

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 MediumCVSS: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-mq976.8

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 MediumCVSS: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

Affected packages
PackageAffectedFixed
svix
crates.io
before 1.17.0
1.17.0
svix
crates.io
0.0.0-0 up to 1.17.0
1.17.0

History

History
RecordedChangedSources
affected
first indexedCVE 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.

References

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