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Fencer Vulns
medium 6.8

CVE-2026-16615 json

Librest: weak random number generation in pkce implementation

published 2026-07-22 3 mo ago modified 2026-09-01 2 mo ago also EUVD-2026-47742

cvss
6.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 38%
public exploits
0
none known

Summary

A flaw was found in librest. The PKCE implementation for OAuth authorization uses the GRand function from the GLib API, a cryptographically insecure pseudo-random number generator. Because the generated "code verifier" lacks sufficient cryptographic entropy, a malicious actor can reverse-engineer the pseudo-random number generator (PRNG) seed to predict or reconstruct the code verifier string, allowing an attacker to bypass PKCE protections and successfully impersonate the client during the OAuth 2.0 authorization flow.

Patch / fix

  • Red Hat Red Hat Enterprise Linux 10 0:0.9.1-11.el10_2.1
  • Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support 0:0.9.1-11.el10_0.1
  • rest RHEL 10.2 0.9.1-11.el10_2.1
  • rest enterprise linux eus 10.0 0.9.1-11.el10_0.1

red hat advisories RHSA-2026:62222RHSA-2026:47085

  • librest SLES for SAP applications 16.0, SLES 16.0 0.9.1-160000.3.1
  • librest0_7 SLE Workstation Extension 15 SP7 0.8.1-150600.4.3.1
  • librest SLE Module for Desktop Applications 15 SP7 0.9.1-150600.3.3.1
  • librest SLES LTSS Extended Security 12 SP5 0.8.0-13.3.1

suse advisories SUSE-SU-2026:23564-1SUSE-SU-2026:3834-1SUSE-SU-2026:3796-1SUSE-SU-2026:3795-1

  • librest openSUSE Leap 16.0 0.9.1-160000.3.1
  • librest0_7 openSUSE Leap 16.0 0.8.1-bp160.2.1
  • librest openSUSE Tumbleweed 0.10.2-2.1

opensuse advisories openSUSE-SU-2026:21694-1openSUSE-SU-2026:21563-1openSUSE-SU-2026:11477-1

  • rest AlmaLinux 10 0.9.1-11.el10_2.1

almalinux advisories ALSA-2026:47085

  • rest Rocky Linux 10 0.9.1-11.el10_2.1

rocky linux advisories RLSA-2026:47085

  • rest Azure Linux 3.0 0.9.0-2

azure linux advisories AZL-93303

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-16615 updated cvss 6.8

librest: weak random number generation in PKCE implementation

  • Red Hat Enterprise Linux AppStream (v. 10) rest 0.9.1-11.el10_2.1
    fixed: vendor fix “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.” RHSA-2026:47085
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) rest 0.9.1-11.el10_0.1
    fixed: vendor fix “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.” RHSA-2026:62222
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) rest-devel 0.9.1-11.el10_2.1, rest-debuginfo 0.9.1-11.el10_2.1, rest-debugsource 0.9.1-11.el10_2.1, rest-demo-debuginfo 0.9.1-11.el10_2.1
    fixed: vendor fix “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.” RHSA-2026:47085
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) rest-devel 0.9.1-11.el10_0.1, rest-debuginfo 0.9.1-11.el10_0.1, rest-debugsource 0.9.1-11.el10_0.1, rest-demo-debuginfo 0.9.1-11.el10_0.1
    fixed: vendor fix “Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.” RHSA-2026:62222

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
3 mo ago

Exploit prediction

0.43% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N

Affected products

  • GNOME librest
  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support

Classification

Weakness
  • CWE-338 Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.