CVE-2023-5981 | Gnutls: timing side-channel in the rsa-psk authentication

A vulnerability was found that the response times to malformed ciphertexts in RSA-PSK ClientKeyExchange differ from response times of ciphertexts with correct PKCS#1 v1.5 padding.

Published: 2023-11-28 Last update: 2026-03-25 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-5981 is rated Moderate Risk (49.7/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.84%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2023-5981

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-19 0.92% 0.84% -0.07%
2 2026-03-26 0.59% 0.92% +0.33%
3 2025-11-28 — 0.59% —

Full EPSS history (29 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-5981

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 3.6 [email protected]
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 3.6 [email protected]

Weakness enumeration for CVE-2023-5981

OS Trackers for CVE-2023-5981

vendor priority summary link
alpine — CVE-2023-5981: 1 source package rows (gnutls); 6 state rows across 6 repos (3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 6, open 0. https://security.alpinelinux.org/vuln/CVE-2023-5981
debian not yet assigned CVE-2023-5981 not yet assigned priority: Debian including 1 source packages (gnutls28), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2023-5981
gentoo normal CVE-2023-5981: 1 GLSA(s) (202411-06), 1 atom(s) (net-libs/gnutls); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2023-5981
redhat medium — https://access.redhat.com/security/cve/CVE-2023-5981
suse medium CVE-2023-5981 severity moderate: SUSE including 327 source package names (15.1.6.2.857:libgnutls30-3.6.7-150000.6.50.1, 15.2.9.5.419:libgnutls30-3.6.7-150200.14.31.1, …), 682 product×package rows across 206 product lines (Container bci/php, Container bci/php-apache, … (206 product lines)): Fixed 438, Known Affected 195, Will Not Fix 36, Known Not Affected 13. https://www.suse.com/security/cve/CVE-2023-5981/
ubuntu medium CVE-2023-5981 medium priority: Ubuntu including 1 source packages (gnutls28), 8 status rows across 8 suites (bionic, focal, jammy, lunar, mantic, trusty, upstream, xenial): released 6, ignored 2. https://ubuntu.com/security/CVE-2023-5981

Affected software / configurations for CVE-2023-5981

Vendor Product Version Raw CPE
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
gnu gnutls < 3.8.2 cpe:2.3:a:gnu:gnutls:*:*:*:*:*:*:*:*
redhat linux 8.0 cpe:2.3:o:redhat:linux:8.0:*:*:*:*:*:*:*
redhat linux 9.0 cpe:2.3:o:redhat:linux:9.0:*:*:*:*:*:*:*
fedoraproject fedora 37 cpe:2.3:o:fedoraproject:fedora:37:*:*:*:*:*:*:*
fedoraproject fedora 38 cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:*

References for CVE-2023-5981

URL Tags
https://access.redhat.com/errata/RHSA-2024:0155 Third Party Advisory
https://access.redhat.com/errata/RHSA-2024:0319 Third Party Advisory
https://access.redhat.com/errata/RHSA-2024:0399 Third Party Advisory
https://access.redhat.com/errata/RHSA-2024:0451 Third Party Advisory
https://access.redhat.com/errata/RHSA-2024:0533 Third Party Advisory
https://access.redhat.com/errata/RHSA-2024:1383 Third Party Advisory
https://access.redhat.com/errata/RHSA-2024:2094 Third Party Advisory
https://access.redhat.com/security/cve/CVE-2023-5981 Vendor Advisory Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2248445 Issue Tracking Third Party Advisory
https://gnutls.org/security-new.html#GNUTLS-SA-2023-10-23 Issue Tracking Vendor Advisory
http://www.openwall.com/lists/oss-security/2024/01/19/3 Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/11/msg00016.html Third Party Advisory
https://lists.fedoraproject.org/archives/list/[email protected]/message/7ZEIOLORQ7N6WRPFXZSYDL2MC4LP7VFV/ Broken Link
https://lists.fedoraproject.org/archives/list/[email protected]/message/GNXKVR5YNUEBNHAHM5GSYKBZX4W2HMN2/ Broken Link
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