How severe is CVE-2026-8503?

CVE-2026-8503 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-8503 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-8503?

CVE-2026-8503 affects Guimard Apache. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-8503?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-8503 have an EU (EUVD) identifier?

Yes. CVE-2026-8503 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30536.

When was CVE-2026-8503 published?

CVE-2026-8503 was published on 2026-05-15 and last updated on 2026-06-17.

CVE-2026-8503

CVE-2026-8503 is a medium-severity vulnerability in Guimard Apache with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-338.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 0% (15th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-30536
Weakness: CWE-338
Affected product: Guimard Apache
Published: 2026-05-15
Last modified: 2026-06-17

Description

Apache::Session::Generate::SHA256 versions before 1.3.19 for Perl create insecure session ids. Apache::Session::Generate::SHA256 generated session ids insecurely. The default session id generator returns a SHA-256 hash of the built-in rand() function, the epoch time, and the PID, that is hashed again. These are predictable, low-entropy sources. Predicable session ids could allow an attacker to gain access to systems. Note that version 1.3.19 has a fallback without warning to use insecure session generation method if the call to Crypt::URandom::urandom fails. However, this is unlikely as Crypt::URandom is a hardcoded requirement of the module. This issue is similar to CVE-2025-40931 for Apache::Session::Generate::MD5.

Frequently asked questions

What is CVE-2026-8503?: Apache::Session::Generate::SHA256 versions before 1.3.19 for Perl create insecure session ids. Apache::Session::Generate::SHA256 generated session ids insecurely. The default session id generator returns a SHA-256 hash of the built-in rand() function, the epoch time, and the PID, that is hashed again. These are predictable, low-entropy sources. Predicable session ids could allow an attacker to gain access to systems. Note that version 1.3.19 has a fallback without warning to use insecure session generation method if the call to Crypt::URandom::urandom fails. However, this is unlikely as Crypt::URandom is a hardcoded requirement of the module. This issue is similar to CVE-2025-40931 for Apache::Session::Generate::MD5.
How severe is CVE-2026-8503?: CVE-2026-8503 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-8503 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-8503?: CVE-2026-8503 affects Guimard Apache. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-8503?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-8503 have an EU (EUVD) identifier?: Yes. CVE-2026-8503 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30536.
When was CVE-2026-8503 published?: CVE-2026-8503 was published on 2026-05-15 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:guimard:apache\:\:session\:\:generate\:\:sha256:*:*:*:*:*:perl:*:*

Other CWE-338 vulnerabilities

CVE-2026-56141 — Critical (CVSS 9.8): In JetBrains Hub before 2026.1.13757, 2025.3.148033, 2025.2.148048, 2025.1.148120, 2024.3.148430, 2024.2.148429 account…
CVE-2026-3256 — Critical (CVSS 9.8): HTTP::Session versions before 0.54 for Perl defaults to using insecurely generated session ids. HTTP::Session defaults…
CVE-2025-15604 — Critical (CVSS 9.8): Amon2 versions before 6.17 for Perl use an insecure random_string implementation for security functions. In versions…
CVE-2025-40926 — Critical (CVSS 9.8): Plack::Middleware::Session::Simple versions before 0.05 for Perl generates session ids insecurely. The default session…
CVE-2026-2439 — Critical (CVSS 9.8): Concierge::Sessions versions from 0.8.1 before 0.8.5 for Perl generate insecure session ids. The generate_session_id…
CVE-2025-15578 — Critical (CVSS 9.8): Maypole versions from 2.10 through 2.13 for Perl generates session ids insecurely. The session id is seeded with the…

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