⚠ Reference material — not professional advice. Test in staging, back up first, verify against your specific version. Use your own judgment for your environment.
● Medium · CVSS 5.9

How to Fix CVE-2026-5080: CWE-340 Generation of Predictable Numbers or Identifiers

By Sai Kiran Pandrala

Other vulnerabilities in the same area that are worth patching alongside this one:

Last verified: 2026-05-25

CVE-2026-5080 is a cwe-340 generation of predictable numbers or identifiers in BIGPRESH Dancer::Session::Abstract. Fix it by upgrading to the patched build from the vendor advisory.

⚡ At a glance
SeverityCVSS 5.9 - Medium
Actively exploited?Not currently in the CISA KEV catalog
AffectedDancer::Session::Abstract 0 up to (including) 1.3522
Fixed inSee vendor advisory
Type (CWE)CWE-340: CWE-340 Generation of Predictable Numbers or Identifiers

What is CVE-2026-5080?

CVE-2026-5080 is a cwe-340 generation of predictable numbers or identifiers flaw in BIGPRESH Dancer::Session::Abstract. It carries a CVSS base score of 5.9 (medium). It is not currently listed in the CISA Known Exploited Vulnerabilities catalog.

From the source record: Dancer::Session::Abstract versions through 1.3522 for Perl generates session ids insecurely.

The session id is generated from summing the character codepoints of the absolute pathname with the process id, the epoch time and calls to the built-in rand() function to return a number between 0 and 999-billion, and concatenating that result three times.

The path name might be known or guessed by an attacker, especially for applications known to be written using Dancer with standard installation locations.

The epoch time can be guessed by an attacker, and may be leaked in the HTTP header.

The process id comes from a small set of numbers, and workers may have sequential process ids.

The built-in rand() function is seeded with 32-bits and is considered unsuitable for security applications.

Predictable session ids could allow an attacker to gain access to systems.

Why it matters in practice: The blast radius depends on how the affected service is exposed. An internet-facing instance with no compensating controls is the highest-risk configuration.

Am I affected?

You are affected if your installation of Dancer::Session::Abstract matches a version listed in the Affected row above.

Check the running version against the Affected row above using the product's admin console or --version flag.

How to fix CVE-2026-5080

Apply the vendor patch. Target the build named in the Fixed in row above (See vendor advisory). The runnable command set below covers the most common deployment patterns for Dancer::Session::Abstract.

Generic upgrade pattern

If the affected product is a Linux package, upgrade via the system package manager:


# Debian / Ubuntu
sudo apt-get update && sudo apt-get upgrade -y

# RHEL / Rocky / Alma
sudo dnf upgrade --security -y

If it ships as a Windows installer, download the patched build from the vendor advisory and:


# Vendor advisory: https://security.metacpan.org/patches/D/Dancer/1.3522/CVE-2026-5080-r1.patch
Start-Process msiexec.exe -ArgumentList '/i <patched-installer>.msi /qn /norestart' -Wait
Get-ItemProperty HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\* | \
    Where-Object DisplayName -match '<product-name>' | Select-Object DisplayName, DisplayVersion

After applying the patch

  1. Restart the service or device so the patched binary loads.
  2. Confirm the running version matches the Fixed in row using the verification command below.
  3. Rotate credentials and API keys that the affected service could access if the asset was exposed during the disclosure window.

If you can't patch immediately

Until the patch lands, narrow the attack surface with these runnable controls.

Restrict network exposure

Block public access to the affected service at the perimeter. Allow only trusted source IPs.


# Linux iptables: only allow trusted admin subnet
sudo iptables -A INPUT -p tcp --dport 443 -s 10.10.10.0/24 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 443 -j DROP
sudo iptables-save | sudo tee /etc/iptables/rules.v4


# Windows firewall: only allow trusted admin subnet on management port
New-NetFirewallRule -DisplayName "Restrict-Mgmt-Allow" -Direction Inbound -Action Allow `
  -RemoteAddress 10.10.10.0/24 -Protocol TCP -LocalPort 443
New-NetFirewallRule -DisplayName "Restrict-Mgmt-Deny"  -Direction Inbound -Action Block `
  -Protocol TCP -LocalPort 443

Mitigations are temporary. Apply the vendor patch as soon as a maintenance window opens.

How to verify the fix worked

Confirm the patched build is the one actually running.

Check the running version against the Affected row above using the product's admin console or --version flag.

Expected: a version at or above the patched build named in the vendor advisory.

Also worth doing: pull recent log windows for indicators of compromise listed in the vendor advisory, and re-run an authenticated vulnerability scan with up-to-date signatures.

Frequently asked questions

Is CVE-2026-5080 being exploited in the wild?

As of 2026-05-25, CVE-2026-5080 is not listed in the CISA Known Exploited Vulnerabilities catalog. Watch the catalog and patch on a normal cadence; KEV status can change as exploitation evidence emerges.

What is the CVSS score for CVE-2026-5080?

The CVSS base score is 5.9 (Medium).

What version fixes this?

The vendor advisory names the patched build. See the References section.

Will a WAF or IDS rule alone close this?

No. Network filters cut down opportunistic scans but they do not remove the flaw. The vendor patch is the only durable fix.

References

*Assembled from the official vendor advisory, the NVD record, and the CISA KEV listing on 2026-05-25. Always confirm against the vendor advisory before applying changes in production.*