Evidence used
- CISA confirms exploitation in the wild.
- A structured source references public exploit or proof-of-concept material.
- EPSS is 84.55% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2020
CVE-2020-28949High confidence
PEAR Archive_Tar Deserialization of Untrusted Data Vulnerability
PEAR · Archive_Tar
7.8HighCVSS 3.1
Mitigate now
Mitigation availableCISA confirms exploitation in the wild and lists 2022-09-15 as the remediation due date.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:Critical, raised one band.upgradedsince 25 Aug 2022
Compensating controls
- Apply the linked authoritative mitigation while planning the permanent fix.
- Restrict local access and enforce least privilege on affected hosts.
- Increase monitoring for the attack path and post-exploitation behaviour described in the report.
Verification
- Confirm that the asset runs PEAR Archive_Tar and falls inside the recorded affected range.
- Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Distribution package intelligence
4 package statesRelease-specific package status
Debian findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.
Repository candidate not checked
A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.
| Distribution release | Source package | Vendor state | Fixed version | Evidence |
|---|---|---|---|---|
| Debian trixietrixie · source | php-pear | Vendor fix publishedDebian records a fixed source-package version for this release. | 1:1.10.9+submodules+notgz-1.1 | Debian Security Tracker ↗Source updated 5 Oct 2026 |
| Debian bookwormbookworm · source | php-pear | Vendor fix publishedDebian records a fixed source-package version for this release. | 1:1.10.9+submodules+notgz-1.1 | Debian Security Tracker ↗Source updated 5 Oct 2026 |
| Debian forkyforky · source | php-pear | Vendor fix publishedDebian records a fixed source-package version for this release. | 1:1.10.9+submodules+notgz-1.1 | Debian Security Tracker ↗Source updated 5 Oct 2026 |
| Debian sidsid · source | php-pear | Vendor fix publishedDebian records a fixed source-package version for this release. | 1:1.10.9+submodules+notgz-1.1 | Debian Security Tracker ↗Source updated 5 Oct 2026 |
Open-source package ranges1 source-attributed range
These OSV and GitHub advisory ranges apply only to the named package and ecosystem. A listed fixed version is not a universal product patch or proof that an update is installed.
| Ecosystem and package | Affected range | First fixed version | Evidence |
|---|---|---|---|
| composerpear/archive_tar | < 1.4.11 | 1.4.11 | GitHub advisory ↗github reviewed aggregator · 22 Oct 2025 |
CISA confirms exploitation in the wild and lists 2022-09-15 as the remediation due date.
Mitigation available01
What, why and how
PEAR Archive_Tar allows an unserialization attack because phar: is blocked but PHAR: is not blocked. PEAR stands for PHP Extension and Application Repository and it is an open-source framework and distribution system for reusable PHP components with known usage in third-party products such as Drupal Core and Red Hat Linux.
What
PEAR Archive_Tar allows an unserialization attack because phar: is blocked but PHAR: is not blocked. PEAR stands for PHP Extension and Application Repository and it is an open-source framework and distribution system for reusable PHP components with known usage in third-party products such as Drupal Core and Red Hat Linux.
Why
The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.
How
An attacker operating through local access may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
PEAR Archive_Tar allows an unserialization attack because phar: is blocked but PHAR: is not blocked. PEAR stands for PHP Extension and Application Repository and it is an open-source framework and distribution system for reusable PHP components with known usage in third-party products such as Drupal Core and Red Hat Linux.
Why
The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.
How
An attacker operating through local access may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation Confirmed in the wild
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.CISA added this CVE to its Known Exploited Vulnerabilities catalogue on 2022-08-25.
Public PoC / exploit material Reference recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.
- Likely attack path
- local access → Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Local
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- Required interaction required
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Unchanged: impact remains within the vulnerable component's security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-74 ↗
CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection'). The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.- Post-exploitation / living off the land
- The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Mitigation available
- Affected
- n/a
- Action
- Apply updates per vendor instructions.
- Workaround
- No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04
Evidence and provenance
Published 19 Nov 2020 · Last source change 21 Oct 2025, 23:35 UTC · CWE-74 · Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2021-0783
Product sourceCISA KEV
Remediation sourceCVE/CNA references
CWE sourceCISA KEV
NVD statusNVD enriched
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
- Vendor guidanceAuthoritative vendor guidance changed: removed remediation: knvd.krcert.or.kr/detail?id=63063cf0d082fd0d2a52dbb9.github.com ↗
- Before
- remediation: knvd.krcert.or.kr/detail?id=63063cf0d082fd0d2a52dbb9 · vendor advisory: github.com/33
- After
- vendor advisory: github.com/33
- Remediation statusRemediation status changed from Mitigation available to Awaiting fix.github.com ↗
- Before
- Mitigation available
- After
- Awaiting fix
- Affected versionsThe structured affected or fixed version information changed.CISA KEV ↗
- Before
- n/a: n/a · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- After
- n/a · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- Affected versionsThe structured affected or fixed version information changed.CNA ↗
- Before
- n/a · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- After
- n/a: n/a · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- Remediation statusRemediation status changed from Awaiting fix to Mitigation available.KISA KrCERT/CC ↗
- Before
- Awaiting fix
- After
- Mitigation available
CVE published
Added to CISA KEV
Remediation guidance recorded
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.