CVE-2026-33996
LibJWT has NULL/bounds validation in JWK octet and RSA PSS parsing
LibJWT is a C JSON Web Token Library. Starting in version 3.0.0 and prior to version 3.3.0, the JWK parsing for RSA-PSS did not protect against a NULL value when expecting to parse JSON string values. A specially crafted JWK file could exploit this behavior by using integers in places where the code expected a string. This was fixed in v3.3.0. A workaround is available. Users importing keys through a JWK file should not do so from untrusted sources. Use the jwk2key tool to check for validity of a JWK file. Likewise, if possible, do not use JWK files with RSA-PSS keys.
Attack profile
How easy it is to exploit
- Attack vector
- Adjacent network
- Complexity
- High
- Privileges needed
- None
- User interaction
- Active
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
5.8
LibJWT has NULL/bounds validation in JWK octet and RSA PSS parsing
LibJWT is a C JSON Web Token Library. Starting in version 3.0.0 and prior to version 3.3.0, the JWK parsing for RSA-PSS did not protect against a NULL value when expecting to parse JSON string values. A specially crafted JWK file could exploit this behavior by using integers in places where the code expected a string. This was fixed in v3.3.0. A workaround is available. Users importing keys through a JWK file should not do so from untrusted sources. Use the jwk2key tool to check for validity of a JWK file. Likewise, if possible, do not use JWK files with RSA-PSS keys.
- Record
CVE-2026-33996- CVSS 4.0
- 5.8 Medium
CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:A/VC:L/VI:L/VA:H/SC:L/SI:L/SA:L - Weakness
- CWE-476
- Updated
- 2026-11-02
EUVDEUVD-2026-16899
5.8
LibJWT is a C JSON Web Token Library. Starting in version 3.0.0 and prior to version 3.3.0, the JWK parsing for RSA-PSS did not protect against a NULL value when expecting to parse JSON string values. A specially crafted JWK file could exploit this behavior by using integers in places where the code expected a string. This was fixed in v3.3.0. A workaround is available. Users importing keys through a JWK file should not do so from untrusted sources. Use the jwk2key tool to check for validity of a JWK file. Likewise, if possible, do not use JWK files with RSA-PSS keys.
- Record
EUVD-2026-16899- CVSS 4.0
- 5.8 Medium
CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:A/VC:L/VI:L/VA:H/SC:L/SI:L/SA:L - Updated
- 2026-11-02
NVD
5.8
LibJWT is a C JSON Web Token Library. Starting in version 3.0.0 and prior to version 3.3.0, the JWK parsing for RSA-PSS did not protect against a NULL value when expecting to parse JSON string values. A specially crafted JWK file could exploit this behavior by using integers in places where the code expected a string. This was fixed in v3.3.0. A workaround is available. Users importing keys through a JWK file should not do so from untrusted sources. Use the jwk2key tool to check for validity of a JWK file. Likewise, if possible, do not use JWK files with RSA-PSS keys.
- Record
CVE-2026-33996- CVSS 4.0
- 5.8 Medium
CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:A/VC:L/VI:L/VA:H/SC:L/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 5.5 Medium
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H - Weakness
- CWE-476
- Updated
- 2026-11-02
OSV
5.8
LibJWT has NULL/bounds validation in JWK octet and RSA PSS parsing
LibJWT is a C JSON Web Token Library. Starting in version 3.0.0 and prior to version 3.3.0, the JWK parsing for RSA-PSS did not protect against a NULL value when expecting to parse JSON string values. A specially crafted JWK file could exploit this behavior by using integers in places where the code expected a string. This was fixed in v3.3.0. A workaround is available. Users importing keys through a JWK file should not do so from untrusted sources. Use the jwk2key tool to check for validity of a JWK file. Likewise, if possible, do not use JWK files with RSA-PSS keys.
- Record
CVE-2026-33996- CVSS 4.0
- 5.8 Medium
CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:A/VC:L/VI:L/VA:H/SC:L/SI:L/SA:L - Weakness
- CWE-476
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2026-33996
5.5
LibJWT is a C JSON Web Token Library. Starting in version 3.0.0 and prior to version 3.3.0, the JWK parsing for RSA-PSS did not protect against a NULL value when expecting to parse JSON string values. A specially crafted JWK file could exploit this behavior by using integers in places where the code expected a string. This was fixed in v3.3.0. A workaround is available. Users importing keys through a JWK file should not do so from untrusted sources. Use the jwk2key tool to check for validity of a JWK file. Likewise, if possible, do not use JWK files with RSA-PSS keys.
- Record
DEBIAN-CVE-2026-33996- CVSS 3.1
- 5.5 Medium
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-33996
5.8
LibJWT is a C JSON Web Token Library. Starting in version 3.0.0 and prior to version 3.3.0, the JWK parsing for RSA-PSS did not protect against a NULL value when expecting to parse JSON string values. A specially crafted JWK file could exploit this behavior by using integers in places where the code expected a string. This was fixed in v3.3.0. A workaround is available. Users importing keys through a JWK file should not do so from untrusted sources. Use the jwk2key tool to check for validity of a JWK file. Likewise, if possible, do not use JWK files with RSA-PSS keys.
- Record
UBUNTU-CVE-2026-33996- CVSS 4.0
- 5.8 Medium
CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:A/VC:L/VI:L/VA:H/SC:L/SI:L/SA:L - CVSS 3.1
- 5.5 Medium
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
libjwt3Debian:14 |
before 3.3.2-1, plus listed versions 3.2.2-13.2.3-1 |
3.3.2-1 |
libjwtUbuntu:18.04:LTS |
All versions, plus listed versions 1.8.0+dfsg-11.8.0+dfsg-21.9.0-11.9.0-1build1 |
None known |
libjwtUbuntu:20.04:LTS |
All versions, plus listed versions 1.10.2-1 |
None known |
libjwtUbuntu:22.04:LTS |
All versions, plus listed versions 1.10.2-11.10.2-1build1 |
None known |
libjwtUbuntu:24.04:LTS |
All versions, plus listed versions 1.10.2-1build11.17.0-21.17.0-2build11.17.0-2build2 |
None known |
libjwtUbuntu:25.10 |
All versions, plus listed versions 1.17.2-1 |
None known |
libjwtUbuntu:26.10 |
All versions, plus listed versions 1.17.2-1build11.17.2-1build2 |
None known |
libjwt3Ubuntu:26.10 |
All versions, plus listed versions 3.2.3-13.3.3-13.3.3-1build1 |
None known |
libjwtUbuntu:26.04:LTS |
All versions, plus listed versions 1.17.2-11.17.2-1build1 |
None known |
libjwt3Ubuntu:26.04:LTS |
All versions, plus listed versions 3.2.2-13.2.3-1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-33996 is a medium vulnerability (CVSS 5.8) in Benmcollins Libjwt, published March 27, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.16%, the 4th percentile. Fixed in libjwt3 3.3.2-1.
References
github.com/benmcollins/libjwt/security/advisories/GHSA-ph96-hqpc-9f66
github.com/benmcollins/libjwt/commit/cfd890286fa49ae61b534c937c9f0428b5c6034c
github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33996.json
nvd.nist.gov/vuln/detail/CVE-2026-33996
security-tracker.debian.org/tracker/CVE-2026-33996
ubuntu.com/security/CVE-2026-33996
cve.org/CVERecord?id=CVE-2026-33996