tenable:216425 · Ubuntu 20.04 LTS / 22.04 LTS / 24.04 LTS : Symfony vulnerabilities…

01 · The Real Story

This is a box of fiddly lock defects, not a vault door blown off its hinges

tenable:216425 is not one bug; it is Ubuntu's February 18, 2025 rollup for multiple Symfony issues in the php-symfony source package (USN-7272-1). The meaningful items range from query-string-driven environment/debug tampering (CVE-2024-50340) to programmatic login bypass edge cases (CVE-2024-50341) and remember-me cookie auth bypass (CVE-2024-51996), plus lower-impact information leaks, open redirect, XSS, and CSRF bugs. Ubuntu fixed these in 24.04 LTS: 6.4.5+dfsg-3ubuntu3+esm1, 22.04 LTS: 5.4.4+dfsg-1ubuntu8+esm1, and 20.04 LTS: 4.3.8+dfsg-1ubuntu1+esm2, with several of the newer CVEs affecting only 22.04/24.04 or only 24.04.

Tenable labels the plugin HIGH, and if someone told you this was CRITICAL, that's overstated. The real-world story is that exploitation is highly app- and configuration-dependent: you need a live Symfony application, the relevant component in use, and often a specific deployment choice like register_argc_argv=On, remember-me persistence, or custom programmatic login flows. There is no KEV listing, no broad exploitation signal, and no generic one-request RCE here.

"High in the scanner, medium in the real world: app-specific Symfony flaws, not a turnkey Ubuntu compromise."

02 · The Attack Path

4 steps from start to impact.

STEP 01

Find a real Symfony target behind the Ubuntu host

An attacker first has to identify an actual internet-reachable Symfony application, not just an Ubuntu box with php-symfony packages installed. Typical tooling is httpx/curl plus response fingerprinting, framework error-page clues, or route behavior mapping. A local package finding on a server that never serves a Symfony app is noise, not exposure.

Conditions required:

Target runs a reachable web application built on Symfony
The vulnerable component is actually installed and loaded by that app

Where this breaks in practice:

Many Ubuntu hosts with the package are build nodes, CI runners, or internal apps
Reverse proxies and generic PHP stacks often hide framework fingerprints

Detection/coverage: Nessus local checks are good at package presence, but they do not prove an exposed or reachable vulnerable code path.

STEP 02

Confirm the specific vulnerable feature is in play

The attacker then has to line up the right bug with the right deployment. For CVE-2024-50340, that means a Symfony Runtime path plus register_argc_argv=On; for CVE-2024-50341, the app must use Security::login programmatically with a custom user_checker; for CVE-2024-51996, the app must use persisted remember-me cookies. Burp Suite or hand-crafted curl requests are enough to test behavior, but the preconditions are narrow.

Conditions required:

App uses the affected Symfony component
App is on an affected Ubuntu branch/version
The feature is enabled in that application design

Where this breaks in practice:

Most enterprises do not use every Symfony component or auth pattern
Several CVEs in this bundle do not affect 20.04 at all; some only hit 24.04

Detection/coverage: SCA and package scanners catch version ranges; DAST usually misses these unless you have app-aware test cases for each feature.

STEP 03

Deliver a crafted request, cookie, or URL

Exploitation is usually logic abuse, not memory corruption. Examples include a crafted query string to influence runtime environment/debug handling, a forged persisted remember-me cookie, or a specially formed URL for open redirect. This is low-skill once the app-specific preconditions are met, but there is no universal exploit string that works across all Symfony apps.

Conditions required:

Attacker can reach the relevant endpoint or auth flow
Application trusts the affected code path during request processing

Where this breaks in practice:

Modern apps often do not expose debug-sensitive behavior externally
Remember-me and programmatic login paths are narrower than generic login pages

Detection/coverage: Web logs, auth logs, and WAF telemetry may show suspicious query-string switches, cookie anomalies, or odd redirect targets; signature coverage is inconsistent.

STEP 04

Convert limited app abuse into business impact

The payoff is usually bounded: auth bypass into one app session, an information leak, an open redirect for phishing, or debug/environment manipulation that may aid further chaining. To reach full host compromise, the attacker typically still needs a second bug, weak secrets, unsafe debug exposure, or post-auth lateral movement. That's the key downgrade pressure here.

Conditions required:

Target app stores useful data or exposes privileged workflows
Attacker can chain the logic flaw into a higher-value objective

Where this breaks in practice:

Most included CVEs do not directly yield code execution on the host
Blast radius is commonly one application or one tenant context, not the whole Ubuntu server

Detection/coverage: App-specific detections matter more than network IDS here; look for impossible login states, remember-me anomalies, and unexpected redirects/debug toggles.

03 · Compensating Control

Prioritize exposed Symfony apps first — Triage this finding by internet reachability and app role, not by raw Ubuntu package count. For a MEDIUM verdict there is no mitigation SLA, but you should still front-load externally exposed Symfony services and admin portals before internal-only or build hosts.

Turn off register_argc_argv where feasible — This specifically cuts risk from CVE-2024-50340 on affected 22.04/24.04 web stacks. Validate PHP runtime defaults and deploy the config change during normal change control if your application does not require argv parsing.

Review remember-me and programmatic login usage — Check whether the application actually uses persisted remember-me cookies or Security::login with custom user checkers. If those features are absent, your reachable risk collapses even if the package scanner still fires.

Harden edge logging and alerting — Add detections for odd query-string switches, unusual redirect targets, and remember-me cookie anomalies so exploitation attempts are visible while you work through remediation. For MEDIUM, this is hygiene rather than an emergency control.

What doesn't work

Generic network blocking doesn't solve this well; the risky behavior lives inside legitimate application request flows on already-allowed web ports.
Relying on WAF alone is weak here; several paths are logic flaws or auth-state mistakes, and signature coverage is inconsistent.
Treating all plugin hits as equally urgent is the wrong control; many hosts with the package are not serving exploitable Symfony code at all.

04 · Intelligence Metadata

The supporting signals.

In-the-wild status	No strong exploitation signal found. The covered Symfony CVEs are not present in CISA KEV based on current KEV catalog review.
KEV status	Not KEV-listed as of the current CISA catalog review; no KEV add date applies.
Proof-of-concept availability	No mainstream weaponized exploit kit surfaced in primary-source review. What is public are vendor advisories, patch commits, and feature-specific descriptions; this looks like patch-diff-driven exploitation, not Metasploit-grade commodity tradecraft.
EPSS	Representative public signal stays low-to-moderate: GitHub shows CVE-2024-50345 EPSS 0.394% (61st percentile). That is not the profile of a hot internet-exploitation bug.
CVSS vector reality check	The scariest score in the bundle is CVE-2024-50340: 7.3 / `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L`, but Ubuntu still assigns it Medium priority because the vulnerable condition is deployment-specific (`register_argc_argv=On`).
Affected Ubuntu ranges	`24.04` and `22.04` carry the newer runtime/network issues; `20.04` is not affected by `CVE-2024-50340` or `CVE-2024-50342`. `CVE-2024-50341` and `CVE-2024-51996` were only addressed for 24.04 in USN-7272-1.
Fixed versions	Ubuntu fixed the source package at `6.4.5+dfsg-3ubuntu3+esm1` (24.04), `5.4.4+dfsg-1ubuntu8+esm1` (22.04), and `4.3.8+dfsg-1ubuntu1+esm2` (20.04). These are Ubuntu backports, so do not compare them naively to upstream Symfony version numbers.
Exposure/scanning data	Internet-scale fingerprinting is weak because this is a library/framework issue, not a clean appliance banner. BitSight still reports a global footprint of 1,384 observations for CVE-2024-50345, which indicates some public presence but not clean enterprise-attributable exposure.
Disclosure timeline	Upstream Symfony advisories landed on November 6, 2024 and November 13, 2024; Ubuntu shipped the rollup notice USN-7272-1 on February 18, 2025.
Researchers / reporting	Named reporters include Sam Mush, Oleg Andreyev, Antoine Makdessi, Moritz Rauch, Linus Karlsson, Chris Smith, Pierre Rudloff, and others across the bundled CVEs.

Sources.

05 · The Call

Final Verdict

↓ DOWNGRADED to MEDIUM (5.1/10)

Why this verdict

Downgrade: package presence is not reachable exposure. Tenable proves Ubuntu package state, not that the host is serving an exploitable Symfony route to attackers.
Downgrade: multiple prerequisites stack. Real attacks need a live Symfony application plus the affected component plus a specific pattern such as register_argc_argv=On, programmatic Security::login, or persisted remember-me cookies.
Downgrade: blast radius is usually application-scoped. Most paths yield auth bypass, info leak, redirect abuse, or debug/env manipulation inside one app, not turnkey host-level code execution.
Downgrade: affected population narrows by release. Some of the most interesting CVEs do not affect 20.04, and some were only addressed for 24.04, which sharply limits broad fleet risk.
Downgrade: no exploitation evidence. Current review found no KEV entry and no strong public campaign signal that would force an urgent threat-driven upgrade.

Why not higher?

This does not earn HIGH or CRITICAL because there is no universal pre-auth RCE path and no evidence that an unauthenticated internet attacker can reliably convert the plugin hit into host compromise across normal Ubuntu deployments. The chain is app-aware and conditional, which is exactly the kind of friction CVSS overstates when you manage 10,000 hosts.

Why not lower?

I would not drop this to LOW or IGNORE because some members of the bundle can still meaningfully weaken exposed production apps. In particular, runtime environment/debug tampering and remember-me or programmatic-login auth issues can create real business impact when they land on an internet-facing Symfony service.

06 · Verification

Crowdsourced verification payload.

Run this on the target Ubuntu host with a regular shell; sudo is only needed if your environment restricts dpkg-query or /etc/os-release. Example: bash verify_symfony_usn7272.sh. The script checks installed php-symfony* packages against the Ubuntu fixed versions for 20.04, 22.04, and 24.04 and prints VULNERABLE, PATCHED, or UNKNOWN.

noisgate-verify.sh

BASHREAD-ONLYSAFE

#!/usr/bin/env bash
# verify_symfony_usn7272.sh
# Check Ubuntu USN-7272-1 (Symfony vulnerabilities) package state.
# Exit codes:
#   0 = PATCHED / not installed
#   1 = VULNERABLE
#   2 = UNKNOWN / unsupported environment

set -u

status_unknown() {
  echo "UNKNOWN: $1"
  exit 2
}

status_vuln() {
  echo "VULNERABLE: $1"
  exit 1
}

status_patched() {
  echo "PATCHED: $1"
  exit 0
}

if [[ ! -r /etc/os-release ]]; then
  status_unknown "/etc/os-release not readable"
fi

# shellcheck disable=SC1091
source /etc/os-release

release="${VERSION_ID:-}"
case "$release" in
  "24.04") fixed="6.4.5+dfsg-3ubuntu3+esm1" ;;
  "22.04") fixed="5.4.4+dfsg-1ubuntu8+esm1" ;;
  "20.04") fixed="4.3.8+dfsg-1ubuntu1+esm2" ;;
  *) status_unknown "Unsupported Ubuntu release: ${release:-unknown}" ;;
esac

if ! command -v dpkg-query >/dev/null 2>&1; then
  status_unknown "dpkg-query not found"
fi

# Collect installed binary packages built from the php-symfony source package naming pattern.
mapfile -t pkgs < <(dpkg-query -W -f='${db:Status-Abbrev}\t${Package}\t${Version}\n' 'php-symfony*' 2>/dev/null | awk '$1 ~ /^ii/ {print $2 "\t" $3}')

if [[ ${#pkgs[@]} -eq 0 ]]; then
  status_patched "No installed php-symfony* packages found"
fi

vuln_found=0
report=""
for line in "${pkgs[@]}"; do
  pkg="${line%%$'\t'*}"
  ver="${line#*$'\t'}"

  if dpkg --compare-versions "$ver" lt "$fixed"; then
    vuln_found=1
    report+="$pkg=$ver (< $fixed); "
  else
    report+="$pkg=$ver (>= $fixed); "
  fi
done

if [[ $vuln_found -eq 1 ]]; then
  status_vuln "USN-7272-1 threshold for Ubuntu $release is $fixed. $report"
else
  status_patched "All installed php-symfony* packages meet or exceed $fixed for Ubuntu $release. $report"
fi